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Cona, Giorgia (2012) Cognitive and electroencephalograohic markers of healthy and pathological aging. [Tesi di dottorato]

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Abstract (inglese)

The present thesis is composed of two main parts. In the first part, the effect of aging was investigated on performance and on event-related potentials (ERPs) associated with several goal-directed cognitive tasks. In the second part, cognitive and ERP changes were explored in patients with minimal hepatic encephalopathy, a syndrome characterized by cognitive and neurophysiological abnormalities in patients with liver cirrhosis.

1° PART: COGNITIVE AND ELECTROPHYSIOLOGICAL ALTERATIONS ASSOCIATED WITH HEALTHY AGING.

It is a truism that as people grow older, performance on a large number of cognitive tasks declines. These age-sensitive tasks include simple and choice reaction times (RTs) tasks, tests of episodic memory, working-memory tasks, tasks involving executive functions, spatial and reasoning abilities, mental rotation (e.g., Kausler, 1991; Salthouse, 1991). Given that deficits are so widespread across the cognitive domains, it is reasonable to assume that a limited number of mechanisms might be responsible. Different theories tried to address this issue. Some of them suggested that cognitive deficits in aging are due to a reduction in the amount of attentional resources (Craik, 1986; Craik & Byrd, 1982), or a slowing down of processing speed (Salthouse, 1996), or a decline in the inhibitory control of working-memory contents (Hasher & Zacks, 1988).
One explanation that has recently gained some prominence is the increasing impairment of executive control with age, likely related to age-specific changes in prefrontal cortex (“theory of Cognitive Control”, also called “goal maintenance account”; Braver & West, 2008; Raz, 2000; West, 1996). Executive control is intended as the ability to represent, maintain and update goal information in order to exert control over behaviour and thoughts (Cohen et al., 1996). According to Miyake and collaborators (2000), executive control is not a single function, but is composed of several cognitive sub-processes, namely shifting, updating and inhibition.
To explore the role of executive control in explaining the age-related cognitive decline, the effect of cognitive aging was measured on those tasks involving high recruitment of such ability. Specifically, the first study of the present thesis (Experiment 1) investigated the age-related changes on a time-based prospective memory (PM) task, and focused on exploring the effect of aging on ERPs. Time-based PM refers to the ability of remembering to perform an action at a specific point in the future, (for example, remembering to attend an appointment at 3 pm; Brandimonte et al., 1996; Einstein & McDaniel, 2000; Kliegel et al., 2009). A fundamental process required for successfully accomplishing PM tasks is the ability to maintain and update the PM intentions (i.e., goal information) active in memory. Such ability, being impaired based on the “theory of cognitive control”, might be the factor determining the age-related alterations observed in time-based PM tasks. The analysis of ERPs elicited in time-based PM tasks is useful to test this hypothesis, and to better clarify the mechanisms responsible for age-related alterations in these kinds of tasks.
The second study focused on the relationship between executive control and cognitive aging by comparing performance of older and younger adults on a task in which the executive control load was manipulated. The task, called Inhibitory Control task (ICT; Bajaj et al., 2008a), is indeed composed of three different conditions, which varies for the executive resources needed. I expected that, if the executive control is the key factor responsible for cognitive impairment in aging, thus the deleterious effect of age on performance would be greater as the executive load increases. Moreover, ICT provides an investigation of the age-related alterations on ERPs associated with the different processes composing executive control, such as updating, shifting, and response inhibition (Miyake et al., 2000).
The two studies will be described in details below.

Experiment 1: ERP mechanisms underlying age-related alterations in Time-Based Prospective Memory.
There is a general agreement, across studies on PM, towards a deleterious effect of age on time-based PM performance (Bastin & Meulemans, 2002; McDaniel & Einstein, 1992; Park et al., 1997; see Henry, MacLeod, Phillips, & Crawford, 2004, for a review).
According to Craik’s theory (Craik, 1986), since in PM tasks there are no explicit prompts from the environment that instigate the retrieval of intention, individuals need to engage self-initiated and attentional demanding processes to retrieve the PM intentions. Given that aging is associated with a reduction in the availability of these attentional resources, thus PM performance would be altered in older people.
On the other hand, according to the “theory of cognitive control” (or “goal maintenance account”; Braver & West, 2008), older adults have difficulties in the maintenance of goal representations over an extended period. In the case of time-based PM, failure to maintain active the goal (i.e., the intention) would lead to failure to correctly execute the intended action.
Although a large number of studies investigated the impairment of time-based PM with aging, nevertheless none study has ever focused on neural activity underpinning such alterations. Therefore, in order to shed light on such poorly investigated issue, the present study explored the age-related alterations in the electrophysiological correlates of time-based PM tasks.
To this end, ERPs associated with ongoing task (i.e., a task executed concurrently with the PM task) were examined in 18 older and 15 younger adults and compared between a baseline block, in which individuals were required to perform merely the ongoing task; and a PM block, in which individuals were required to perform simultaneously the ongoing and the PM tasks. The ongoing task consisted in evaluating in five-letter strings whether the letters in second and fourth positions (target positions) were equal or different by pressing one of two possible keys. In the PM task, participants were required to remember to press the “PM key” every five minutes from the beginning of the block. To help them to estimating the passing of time, they had the opportunity to check the digital clock in any moment of the task by pressing another key. The ERPs were locked to ongoing trials (i.e., the strings of letter). Reaction times, accuracy and ERPs relative to ongoing trials were compared between the baseline and the PM block, for both younger and older adults. Moreover, the percentage of accuracy in PM task and the number of clock checks were recorded.
Concerning the behavioural results, older adults showed a lower percentage of accuracy in PM task respect to younger adults. Moreover, the older adults displayed a slowing down of RTs in the ongoing task, both in the baseline and in PM block, as compared to younger adults.
Concerning the ERPs of younger adults, the addition of a time-based PM task to an ongoing activity led to a sustained positive modulation of the ERPs elicited by the ongoing trials, mainly expressed over prefrontal and frontal regions. This frontal activity seems to reflect the load of maintaining the intention active in memory, as recently suggested (Cona et al., in press; West et al., 2011). On the other hand, in older adults these ERP modulations were more expressed over posterior regions. Interesting, a difference in the ERP amplitude between baseline and PM block was observed over prefrontal sites in younger adults (with the ERPs being more positive in PM block), but not in older adults. At first glance, the absence of the prefrontal mofulation in older adults seems to reflect their difficulties in keeping the PM intention in mind, as suggested by the “theory of cognitive control” (Braver & West, 2008).
Nevertheless, the exploration of the ERP differences as observed between the two groups in the baseline block allowed to better clarify the mechanisms responsible of these age-related changes in PM. Indeed in baseline block, compared to younger adults, older adults showed a lower P300 over parietal regions, and a higher P300 over prefrontal regions. The anteriorisation of the P300 shown by older adults has been well documented in literature (Daffner et al., 2006; 2011), and it is supposed to reflect the greater recruitment of attentional resources to compensate for olders’ difficulties in the ongoing task.
Taken together, these results suggest that older adults had difficulties already in the baseline block, and cope with such difficulties by recruiting additional frontal resources (as reflected by the anteriorisation of P300). If too many resources were allocated to perform the ongoing task, then fewer resources would be available to adequately maintain the intentions in memory, leading to an impaired PM performance. Therefore, it seems more reasonable that the decline in executive control, required for intention maintenance, is not the primary cause of the age-related changes in PM tasks, but rather is itself the consequence of a reduced amount of available resources, as postulated by Craik’s theory (1986).

Experiment 2: Influence of aging on ERP correlates of
executive control processes.
According to the “theory of cognitive control” (Braver & West, 2008), an age-related impairment in executive control is hypothesized to determine specific decrements in those cognitive tasks that are more demanding for that function. In order to test this prediction, we adopted the Inhibitory Control task (ICT; Bajaj et al., 2008a). During the ICT, a continuous stream of letters is presented, very quickly, one after the other. In the first part of the task, it is required to respond by pressing a key only to the target letters (i.e., “X” and “Y,”). Trials containing a target letter are labelled as Detect trials. In the second part, it is required to respond whenever the target letters are alternated (Go trials), as when an “X” is preceded by a “Y”, or vice versa, regardless of the irrelevant letters presented between them. In contrast, it must withhold response if target letters are repeated (Nogo trials), as when an “X” precedes another “X”, or a “Y” precedes another “Y”. In light of this, ICT includes trials requiring different demands of executive control. Detect trials requires to merely pay selective attention and to respond to specific stimuli. These trials are relatively low demanding in terms of executive control. Go trials are more demanding, implying the process of working memory updating. Finally, Nogo trials are the highest demanding trials since imply not only an updating process but also inhibitory control of response. According to the theory of control, differences on ICT performance between younger and older adults should be lowest in detect trials, intermediate in go trials and greatest in nogo trials.
Furthermore, this study was aimed at investigating the effect of age on the different processes composing the executive control (Miyake et al., 2000). Therefore it was explored the influence of aging on peak latency and amplitude of P3b, nogo-P3 and RON (i.e., reorienting negativity) components, which reflect updating, inhibition, and shifting processes, respectively. In order to better dissociate the ERP components related to these different processes, a partial least square (PLS) analysis was run. Seventeen younger and sixteen older adults performed the ICT.
Against the formulated predictions, older adults exhibited a worse performance in all kinds of trial, as from detect trials to nogo trials. More importantly, the age effect did not interact with the type of trials, hence was independent from the degree of executive control required to perform them. This means that executive control, when formulated as a unitary construct responsible for the age-related deficits in cognition, does not seem to be the elective factor for explaining the deficits shown in ICT task. In line with behavioural results, older adults showed a delay in all the ERP components studied (P3b, N2, RON, nogo-P3), regardless of the type of trial. These age-related alterations in the latency of the ERPs seem to reflect a slowing of speed of cognitive processing in the elderly individuals. Such an idea gives support to Sathouse's theory (Salthouse, 1996), which assumed that age-related cognitive decline might be due to a general reduction in the speed of processing.
Another relevant finding consists in the fact that the RON components were found particularly sensitive to aging. Specifically, these components, reflecting attentional shifting (Berti et al., 2008), were shown delayed and reduced in older adults. To my knowledge, only one study has investigated the age-related alterations in the RON components before, but utilizing an auditory distraction-paradigm (Horváth et al., 2009). Thus, the present study extended the results obtained in the work by Horváth, suggesting that the age-related impairment of attentional shifting occurred not only after distracter stimuli (as found by Horváth), but also after task-relevant ones. It suggests that in older adults shifting mechanism of attention take longer and is more effortful, probably because they are still engaged in processing the previous stimulus. Summarizing, electrophysiological and behavioural data converged in revealing that age-related cognitive impairment might be, at least partially, attributable to a general slowing of information processes. Indeed, coherently with the review by Verhaegen (2011), reduction on processing speed seems to explain cognitive deficits in elderly better than deterioration in executive control, when this is conceptualized as a unitary construct. On the other hand, a subprocess of executive control, attentional shifting, resulted particularly affected by age, and it could be another candidate to explain multiple age-related cognitive alterations.

1° Part: Conclusions
Although the present studies utilized different paradigms and tasks, they converged in revealing that executive control does not play a crucial role in determining the age-related deficits seen in these tasks. Rather, a decline in more basic, or lower-level, mechanisms seems to be the key factor to explain the multitude of age-related cognitive deficits. Specifically, the analysis of the ERPs allowed to highlight that age-related alterations were more likely due to a reduction: 1) in the amount of available resources and 2) in processing speed.
The age-related alterations concerned mainly ERPs over prefrontal regions and were they were mainly expressed as delay in the ERP latencies. Interestingly, compensatory mechanisms in older adults were also observed, and were reflected in the increase of amplitude of several components (respect to the younger adults). This led to the suggestion that aging does not simply mean cognitive and neural decline, but may also involve adaptive cognitive and neural responses.

2° PART: COGNITIVE AND ELECTROPHYSIOLOGICAL ALTERATIONS ASSOCIATED WITH MINIMAL HEPATIC ENCEPHALOPATHY.

Hepatic encephalopathy (HE) is a neuropsychiatric syndrome occurring in acute or chronic liver failure. The detection of the first, sometimes apparently negligible, signs of hepatic encephalopathy is greatly important since this condition, called minimal hepatic encephalopathy (MHE; Ferenci et al., 1998), impinges on the health-related quality of life (Groeneweg et al., 1998; Zhou et al. 2009) and it is likely to affect driving ability (Wein et al., 2004). Furthermore, it has a negative prognostic value in relation to the occurrence of both bouts of overt hepatic encephalopathy and death (Amodio et al., 1999; Romero-Gomez et al., 2007). The profile of MHE is characterized by cognitive alterations that involve selective attention and executive functions, visuomotor ability, psychomotor speed, response inhibition, and response selection (Amodio et al., 2005). MHE also causes brain dysfunction detectable by slowing of the electroencephalogram (EEG) and prolonged ERPs, such as P300 (Amodio et al., 2005; Weissenborn et al., 2005). Therefore, where possible, the diagnosis of MHE is preferably based on a combination of psychometric and neurophysiological/psychophysiological tools.
The inhibitory control task (ICT) has been recently proposed as a simple diagnostic tool for MHE (Bajaj et al., 2007; 2008a). However, its applicability to different populations of patients with cirrhosis and its relation to other measures of MHE need to be confirmed. Therefore, Experiment 3 was designed to address this issue and was aimed at assessing the specificity and sensitivity of ICT for the diagnosis of MHE. The Experiment 4 focused on the effect of MHE on the ERPs elicited by ICT, in order to highlight cognitive and electrophysiological alterations characterizing MHE.
In order to further investigate the electrophysiological alterations of MHE, another study (Experiment 5) explored the intra-individual variability (IIV) of P300 parameters (i.e., latency and amplitude) in cirrhotic patients with MHE. There is an increasing interest in IIV of cognitive performance (e.g., of RTs) within the field of cognitive neuroscience (MacDonald et al., 2006), since IIV has been widely considered to be a behavioral indicator of compromised neural mechanisms (e.g., Hultsch, et al., 2000). Nevertheless, studies establishing links between intra-individual variability in behavioral and brain responses are sparse, with most evidence being indirect. MHE seems to be a suitable model of pathology for studying this relation, given that patients with MHE showed increased IIV of RTs (Elssas et al., 1985; Schiff et al., 2006).
Therefore, in Experiment 5, single-trial P300 parameters, obtained by means of a single-trial Bayesian estimation technique (D’Avanzo et al., 2011), were estimated to investigate the electrophysiological correlates of IIV of response speed and the relation between P300 parameters and RTs in normal individuals and in a population of patients with and without MHE.

Experiment 3 and 4:
The ICT as a suitable tool for detecting cognitive and ERP alterations in patients with liver cirrhosis.
In Experiment 3, seventy-five patients with cirrhosis and 55 healthy controls underwent the ICT in 2 reference centers for the study of hepatic encephalopathy. Patients were evaluated for MHE by psychometric hepatic encephalopathy score (PHES) and spectral electroencephalogram analyses. Performance on go and nogo trials was compared between the two groups. Patients with cirrhosis exhibited a higher number of errors in nogo trials (i.e., lures), and lower accuracy in go trials, as compared with controls. However, the number of lures was comparable among patients with and without MHE. Importantly, an inverse relation between accuracy in go trials and number of lures was shown when the go accuracy was particularly low. However this is not surprising: a low accuracy in go trials indicates that many trials had a missing response (in go trial an error is a missed response), but if a participant commits many missing responses, he/she is more likely to “perform” correctly on nogo trials (hence to not respond when actually it is required to not respond). In light of this, the low number of error in nogo trials is a spurious effect. Hence, a new variable (weighted lures) was codified, adjusting the number of lures based on go accuracy. This variable distinguished between patients with and without MHE. However, accuracy in go trials alone was as effective as a stand-alone variable. Therefore, testing inhibition (lures) does not seem to be superior to testing attention and working memory updating (go accuracy) for the detection of MHE.
In Experiment 4 the electrophysiological alterations related to cirrhosis were investigated in the ICT task by comparing ERPs in cirrhotic patients with MHE (N=13), without MHE (N=18) with ERPs in healthy controls (N=17). Specifically, the ERPs in detect, go and nogo trials were measured, reflecting processes of selective attention, working memory updating, and inhibition, respectively. Data were further analysed by means of a PLS analysis, was particularly suited to dissociate the ERP correlates of the different subprocesses. Findings from ANOVA and PLS analysis converged in showing selective alterations of the ERPs on detect trials in patients with MHE. Specifically these included a reduction in P3a amplitude over frontocentral sites and a delay in the P3b latency. Since detect trials involve principally attentional processes, alterations on these trials may indicate that MHE is associated with an impairment of low-level cognitive abilities, such as attention. This result corroborated the claim of Experiment 3, concerning the appropriateness to test for low-level abilities (i.e., attention) before, or together with, testing for high-level abilities (i.e., inhibition) for the diagnosis of MHE (Amodio et al., 2010). The second main, and unexpected, finding was the enhancement of several ERP components (namely, the N2 and nogo-P3) in cirrhotic patients without MHE. These electrophysiological changes might be a compensatory mechanism, reflecting the allocation of additional executive resources for overcoming the difficulties of the task (indeed, also patients without MHE had a reduction of P3a, which is an index of attentional processes).

Experiment 5: The IIV of P300 as an index for detecting neural dysfunctions in patients with liver cirrhosis
In patients with cirrhosis, an increased intra-individual variability of RTs has been described and qualified as a potential early sign of brain dysfunction (Schiff et al., 2006). Unfortunately, a neural counterpart of this phenomenon was not obtained yet. However, since a reduction in the amplitude of P300 has been observed in this patient population, it is possible to hypothesize that P300 amplitude reduction depends, at least in part, on the increased variability of single-trial P300 latency (as evidenced in other pathologies; e.g., Hultsch et al., 2000). Moreover, single-trial analysis might clarify the relation between RTs and P300 parameters, and evidence how this relation changed under pathological conditions, such as MHE.
EEG was recorded during the execution of a choice reaction time task (i.e., Simon task) in 14 cirrhotic patients with MHE (diagnosed on paper & pencil tests plus EEG), 15 cirrhotic patients without MHE and 14 healthy controls matched for age and educational level. Single-trial P300 amplitude and latency, together with their standard deviation, were obtained using a non-parametric bayesian estimation method. P300 was also measured with the classical method of averaging. RTs distribution and its relation with single-trial P300 amplitude and latency were analysed.
In cirrhotic patients, RTs were slower and more variable compared to those of controls. An increased variability in P300 latency was also detected. Linear multiple regression analysis revealed that average-based P300 amplitude reduction was predicted both by standard deviation of single-trial P300 latency and by single-trial P300 mean amplitude.
These results indicate that average-based P300 amplitude reduction in cirrhotic patients with MHE depends on both an increased variability of single-trial P300 latency, and a reduction in single-trial P300 amplitude. Interestingly, we also found that P300 latency increased and amplitude decreased in parallel with increasing RTs in normal participants, but not in cirrhotic patients with MHE. Thus, another sign of neural alteration might be the weaker relationship between RTs and P300 parameters observed in patients with MHE.
In summary, the present study suggests that, under normal conditions, a relation between P300 and RTs is detectable and the P300 is stable across trials; in contrast, when the brain does not function properly, as observed in patients with MHE, the relation between P300 and RTs vanishes, and neural responses become more variable.

2° Part: Conclusions
The use of ICT task provided several insights concerning the neural markers of MHE. Specifically, patients with MHE showed a prolongation and a reduction of the P300 components elicited in the detect trials of ICT task, reflecting deficits in selective and sustained attention. On the other side, patients without MHE displayed an enhancement of several ERP components (i.e., N2 and P3-nogo), which might reflect a compensatory neural mechanism.
The Experiment 5 better clarified the profile of P300 in cirrhotic patients. Indeed, such patients, especially those with MHE, showed an increased intra-individual variability of the P300 latency, which may contribute to the reduction of its amplitude.

GENERAL CONCLUSIONS
The ERP technique was revealed to be a powerful tool to explore neural alterations underlying both the healthy and pathological aging. Interestingly, several patterns of ERP alterations were shared by older individuals and cirrhotic patients (e.g., the delay in several ERPs, or a ‘paradoxical’ enhancement of other components, such as N2). Such ERP alterations highlighted that 1) age- and MHE-related deficits in higher-level cognitive tasks might be due to alterations in lower-level functions or mechanisms, including attention deficits, the reduction of available resources or processing speed; 2) brain activity of older people and cirrhotic patients without MHE was similarly characterized by compensatory mechanisms, recruited to cope with the difficulties of the tasks

Abstract (italiano)

La presente tesi si compone di due parti principali. Nella prima parte è stato studiato l’effetto dell’età sulla performance e sui potenziali evento-relati (ERP) elicitati in differenti compiti cognitivi. Nella seconda parte sono stati esplorati i cambiamenti elettrofisiologici (i.e., alterazioni a livello di ERP) e cognitivi che caratterizzano l’encefalopatia epatica minima (MHE), una sindrome neuropsichiatrica conseguente a cirrosi epatica.

1° PARTE: ALTERAZIONI COGNITIVE ED ELETTROFISIOLOGICHE ASSOCIATE ALL’INVECCHIAMENTO SANO.
All’avanzare dell’età, le persone mostrano difficoltà in diversi compiti cognitivi. Tali compiti comprendono ad esempio compiti di tempi di reazione (TR) semplice o di scelta, test di memoria episodica, compiti di working memory o che coinvolgono funzioni esecutive, abilità spaziali e di ragionamento, test di rotazione mentale (e.g., Kausler, 1991; Salthouse, 1991).
Dato che tali deficit sono così diffusi tra i diversi domini cognitivi, è ragionevole assumere che essi dipendano da un’alterazione a carico di un ristretto numero di meccanismi. Diverse teorie si sono occupate di rispondere a tale questione. Alcune di queste hanno suggerito, ad esempio, che l’invecchiamento cognitivo sia associato ad una riduzione nella quantità di risorse attenzionali disponibili (Craik, 1986; Craik & Byrd, 1982), ad un rallentamento nella velocità di elaborazione (Salthouse, 1996), o ad un declino nel controllo inibitorio delle informazioni contenute nella working memory (Hasher & Zacks, 1988).
Una spiegazione cha ha recentemente ricevuto largo consenso sostiene che alla base delle alterazioni cognitive legate all’età vi sia una disfunzione a livello di controllo esecutivo, probabilmente dovuta a cambiamenti a carico della corteccia prefrontale (“teoria del controllo cognitivo” conosciuta anche come “ipotesi del mantenimento degli obiettivi”; Braver & West, 2008; Raz, 2000; West, 1996). Per controllo esecutivo si intende la capacità di rappresentare, mantenere e aggiornare gli obiettivi in memoria al fine di esercitare un controllo sui pensieri e sul comportamento (Cohen et al., 1996). Sulla base del lavoro di Miyake e collaboratori (2000), il controllo non sembra essere una funzione unitaria, ma è composta da diversi sotto-processi cognitivi, quali lo shifting, l’aggiornamento nella working memory e l’inibizione.
Per esaminare il ruolo che ha il controllo esecutivo nello spiegare il declino cognitivo legato dell’invecchiamento, è stato testato l’effetto dell’età in quei compiti che sono stati dimostrati richiere un alto coinvolgimento di controllo esecutivo. In particolare, il primo studio di questa tesi (Esperimento 1) ha esaminato i cambiamenti, legati all’età, in un compito di memoria prospettica (MP) basata sul tempo, focalizzandosi sull’analisi di quelle modulazioni ERP che rifletterebbero il declino della MP nell’invecchiamento. La memoria prospettica basata sul tempo si riferisce infatti all’abilità di ricordarsi di eseguire un’azione in un particolare momento nel futuro (ad esempio, ricordarsi di andare ad un appuntamento alle tre; Brandimonte et al., 1996; Einstein & McDaniel, 2000; Kliegel et al., 2009). Un processo che è fondamentale per eseguire appropriatamente i compiti prospettici è il mantenimento e l’aggiornamento delle intenzioni prospettiche in memoria (che rappresentano altresì gli obiettivi del compito prospettico). Tali processi di mantenimento, essendo alterati nell’invecchiamento secondo la teoria del controllo cognitivo, potrebbero essere quindi il fattore chiave nel determinare le alterazioni osservate nei compiti di MP. L’analisi degli ERP elicitati dal compito prospettico si è rivelata utile per testare tale ipotesi, e per chiarire quali siano i meccanismi responsabili del declino in questo tipo di compiti.
Il secondo studio ha indagato la relazione tra controllo esecutivo e invecchiamento cognitivo confrontando la prestazione di individui giovani e quella di individui più anziani in un compito in cui veniva variato il carico di controllo esecutivo tra le condizioni. Il compito, chiamato Inhibitory Control Task (ICT) (Bajaj et al., 2008a) è, infatti, composto da tre differenti condizioni, che differiscono per le risorse esecutive necessarie. Se il controllo esecutivo è il fattore chiave nel determinare il deterioramento cognitivo osservato nei diversi compiti, allora l’effetto dell’età sulla performance all’ICT dovrebbe essere tanto maggiore quanto più elevato è il grado di controllo esecutivo richiesto. Inoltre, l’ICT ha permesso di studiare le alterazioni legate all’età negli ERP associati ai differenti meccanismi che compongono il controllo esecutivo, ovverosia l’aggiornamento nella working memory, l’updating e l’inibizione (Miyake et al., 2000).
I due studi saranno qui sotto descritti in dettaglio:

Esperimento 1: Meccanismi ERP sottostanti alle alterazioni, legate all’età, nella memoria prospettica basata sul tempo.
Esiste un generale consenso, tra gli studi sulla MP, riguardo all’effetto deleterio che ha l’invecchiamento sulle prestazioni in compiti di MP basata sul tempo (Bastin & Meulemans, 2002; McDaniel & Einstein, 1992; Park et al., 1997; vedere anche Henry, MacLeod, Phillips, & Crawford, 2004, per una rassegna).
Secondo la teoria di Craik (1986), poiché nei compiti di MP non ci sono espliciti suggerimenti dall’ambiente che aiutano il recupero dell’intenzione, gli individui necessiterebbero di un maggior reclutamento di processi attenzionali e auto-iniziati per recuperare le intenzioni. Dato che l’invecchiamento è associato ad una riduzione nella disponibilità di tali risorse attenzioni, ciò determinerebbe un’alterazione nella prestazione dei compiti di MP negli individui più anziani.
Dall’altra parte, secondo la teoria del controllo cognitivo (o anche detta “ipotesi del mantenimento degli obiettivi”; Braver & West, 2008), gli anziani avrebbero delle difficoltà nella rappresentazione e nel mantenimento degli obiettivi nel corso del tempo. Nel caso della MP basata sul tempo, i deficit nel mantenere attivi gli obiettivi (cioè le intenzioni) porterebbe ad un fallimento nell’eseguire con successo l’azione intesa.
Sebbene un elevato numero di studi abbia esaminato come la MP basata sul tempo declini con l’età, tuttavia nessuno studio si è mai occupato finora di indagare l’attività neurale alla base di tale declino. Per tale motivo, il presente studio ha avuto lo scopo di esplorare le alterazioni legate all’età dei meccanismi elettrofisiologici alla base della MP basata sul tempo.
A tal fine, gli ERP associati ad un compito detto ongoing (i.e., un compito eseguito simultaneamente al compito prospettico) sono stati analizzati in 18 anziani e di 15 giovani e sono stati confrontati tra due diversi blocchi: il blocco di baseline e il blocco prospettico. Nel blocco di baseline veniva chiesto ai partecipanti di eseguire solamente il compito ongoing, mentre nel blocco prospettico si chiedeva di eseguire, assieme al compito ongoing, anche il compito di MP. Il compito ongoing consisteva nel valutare, all’interno di stringhe di cinque lettere, se le lettere in seconda e quarta posizione fossero uguali o diverse premendo con la mano destra uno di due possibili tasti. Nel compito di MP basata sul tempo, ai partecipanti era richiesto di premere un tasto ogni 5 minuti a partire dall’inizio del blocco prospettico. Per aiutarli nella stima del tempo, era stata data loro la possibilità di controllare l’orologio (che sarebbe comparso sullo schermo qualora avessero premuto un ulteriore tasto). Gli ERP analizzati erano elicitati dalla comparsa dello stimolo ongoing (i.e., la stringa di lettere). I TR, l’accuratezza e gli ERP nelle prove ongoing sono stati analizzati confrontando il blocco di baseline e quello prospettico, sia nei giovani che negli anziani. Inoltre sono stati analizzati sia la percentuale di accuratezza nel compito prospettico che il numero di controlli dell’orologio.
Per quanto riguarda i risultati comportamentali, gli anziani mostravano una percentuale di accuratezza inferiore nel compito prospettico rispetto ai giovani. Inoltre gli anziani hanno mostrato un aumento dei TR al compito ongoing rispetto ai giovani, sia nella baseline che nel blocco prospettico.
A livello di dati elettrofisiologici, i giovani hanno mostrato delle modulazioni positive e sostenute degli ERP elicitati dagli stimoli ongoing dovute all’aggiunta del compito prospettico, che erano espresse maggiormente sopra le regioni frontali e prefrontali. Tali modulazioni riflettevano il carico nel mantenere le intenzioni attive in memoria, come recentemente suggerito (Cona et al., in press; West et al., 2011). Dall’altra parte, negli anziani, tali modulazioni erano maggiormente espresse sopra le regioni posteriori. È infatti interessante notare che i giovani, ma non gli anziani, mostravano una maggiore positività degli ERP nel blocco prospettico rispetto alla baseline a livello di siti frontopolari. Ad un primo sguardo, l’assenza della modulazione prefrontale negli anziani sembra riflettere la loro difficoltà nel mantenere in memoria le intenzioni prospettiche, in accordo con la teoria del controllo cognitivo (Braver & West, 2008). Tuttavia, l’analisi delle differenze ERP tra i due gruppi (già nella baseline) ha permesso di comprendere meglio quale fosse il meccanismo responsabile di questo peggioramento nella performance prospettica. Infatti nel blocco di baseline, se confrontati con i giovani, gli anziani mostravano una P300 meno ampia sopra le regioni parietali, e più ampia sopra le regioni prefrontali. L’anteriorizzazione della P300 negli anziani è un fenomeno già ben documentato in letteratura (Daffner et al., 2006; 2011) e sembra indicare il reclutamento di un maggior numero di risorse per compensare le difficoltà nell’eseguire il compito ongoing.
In generale, tali risultati suggeriscono che gli anziani hanno difficoltà già nel blocco di baseline, e che affrontano tali difficoltà reclutando risorse frontali addizionali (come indicato dall’anteriorizzazione della P300). Se troppe risorse sono reclutate per eseguire il compito ongoing, allora ne rimarrebbero meno per mantenere adeguatamente le intenzioni in memoria e ciò determinerebbe una performance peggiore al compito prospettico. Sembra quindi più ragionevole assumere che il declino nel controllo esecutivo, richiesto per mantenere le intenzioni in memoria, non sia la causa primaria dei cambiamenti nei compiti prospettici, ma piuttosto sia a sua volta la conseguenza di una minor disponibilità di risorse cognitive, come postulato nella teoria di Craik (1986).

Esperimento 2: Influenza dell’invecchiamento sugli ERP associati ai processi legati al controllo esecutivo.
Secondo la teoria del controllo cognitivo (Braver & West, 2008), un declino del controllo esecutivo dovuto all’età produrrebbe deficit in quei compiti cognitivi che coinvolgono in misura maggiore proprio quella funzione. Al fine di studiare tale ipotesi, abbiamo utilizzato l’Inhibitory Control Task (ICT; Bajaj et al., 2008a). Durante l’ICT, una serie di lettere viene presentata, molto velocemente, una dopo l’altra. Nella prima parte del compito è richiesto di premere un tasto quando compare o la lettera X o la Y. Le prove in cui compaiono tali lettere vengono definite prove Detect. Nella seconda parte del compito è richiesto di premere il tasto solo quando la X e la Y si alternano (prove Go), ad esempio quando la X è preceduta da una Y, o vice versa, indipendentemente dalle lettere che vengono presentate tra le due lettere target. Quando le lettere X e Y si ripetono (ad esempio, una X è preceduta da un’altra X), allora è necessario inibire la risposta (prove Nogo). In tal modo, l’ICT include prove che richiedono un differente grado di controllo esecutivo per essere eseguite. Infatti, le prove Detect richiedono semplicemente di prestare attenzione selettiva e di rispondere a specifici stimoli, e coinvolgono per questo un basso grado di controllo esecutivo. Le prove Go implicano anche un processo di aggiornamento nella working memory. Infine, le prove Nogo richiedono il maggior carico di controllo esecutivo, coinvolgendo non solo un processo di aggiornamento ma anche l’inibizione di risposta. Sulla base della teoria del controllo cognitivo, le differenze tra giovani e anziani nella prestazione all’ICT dovrebbero essere minori nelle prove detect, intermedie nelle prove go e massime nelle prove nogo.
In aggiunta, questo studio aveva lo scopo di studiare l’effetto dell’età sui singoli processi che compongono il controllo esecutivo (Miyake et al., 2000). Per tale motivo, è stato studiato l’effetto dell’età sull’ampiezza e la latenza della P3b, della P3-nogo e della RON (reorienting negativity) che riflettono rispettivamente i processi di aggiornamento, inibizione e shifting. Al fine di dissociare meglio quali fossero le componenti ERP legate ai differenti processi studiati, è stata condotta la partial least square (PLS) analisi. Diciassette giovani e sedici anziani hanno partecipato all’esperimento ed eseguito l’ICT. Contro le predizioni formulate, i dati comportamentali hanno rivelato come gli anziani avessero una performance peggiore rispetto ai giovani in tutti i tipi di prove, quindi dalle prove detect alle prove nogo. È importante notare che l’effetto dell’età non interagiva con il tipo di prova, ed era quindi indipendente dal grado di controllo esecutivo necessario per eseguire quella data prova. Ciò indica che il controllo esecutivo, quando inteso come costrutto unitario, non sembra essere il fattore elettivo responsabile dei deficit mostrati dagli anziani nell’ICT. In linea con i risultati comportamentali, gli anziani hanno mostrato un ritardo in tutte le componenti ERP indagate (P3b, N2, RON, P3-nogo), indipendentemente dal tipo di prova esaminata. Questo ritardo nella latenza degli ERP legato all’età sembra riflettere un generale rallentamento dei processi cognitivi. Tale idea offre supporto alla teoria di Salthouse (1996), la quale assume che il declino cognitivo legato all’età sia dovuto ad una generale riduzione nella velocità di elaborazione.
Un altro risultato rilevante consiste nel fatto che le componenti RON sono risultate particolarmente sensibili all’invecchiamento. Tali componenti, che riflettono lo shifting attenzionale (Berti et al., 2008), erano ritardate e meno ampie negli anziani rispetto ai giovani. Solamente uno studio finora ha indagato le alterazioni, legate all’età, a carico delle componenti RON, ma utilizzando un paradigma uditivo di distrazione (Horváth et al., 2009). In questo senso il presente studio ha esteso i risultati ottenuti nello studio di Horváth, suggerendo che un declino nello shift attenzionale non avviene solo dopo stimoli distraenti (come evidenziato da Horváth) ma anche dopo stimoli rilevanti per il compito. Sembra, infatti, che negli anziani il meccanismo di shifting dell’attenzione sia più lento e dispendioso, probabilmente a causa del fatto che essi sono ancora occupati ad elaborare lo stimolo precedente.
Riassumendo, i dati elettrofisiologici e comportamentali convergono nel rivelare che il peggioramento nei compiti cognitivi associato all’invecchiamento potrebbe essere, almeno parzialmente, spiegabile da un rallentamento generale di elaborazione delle informazioni. Infatti, coerentemente con le conclusioni formulate nella rassegna di Verheagen (2011), una riduzione nella velocità dei processi sembra spiegare meglio i deficit cognitivi dell’anziano, rispetto ad un possibile deterioramento nel controllo esecutivo (quando inteso come processo unitario). Dall’altra parte, un sottoprocesso del controllo esecutivo, lo shifting attenzionale, sembra essere particolarmente sensibile all’età, e potrebbe quindi rappresentare un possibile candidato per spiegare la molteplicità di deficit nell’anziano.

1° Parte: Conclusioni

Sebbene i presenti studi abbiano utilizzato differenti paradigmi e compiti, tuttavia convergono nel mostrare come il controllo esecutivo non giochi un ruolo cruciale nel determinare i deficit cognitivi evidenziati in questi compiti. Piuttosto, un declino nei processi più di base sembra essere il fattore chiave per spiegare la molteplicità dei deficit cognitivi nell’invecchiamento. In particolare, l’analisi degli ERP ha permesso di evidenziare che i cambiamenti legati all’età sono più probabilmente dovuti ad una riduzione: 1) nella disponibilità delle risorse cognitive, 2) nella velocità di elaborazione.
Le alterazioni elettrofisiologiche legate all’età sembrano interessare in misura maggiore le modulazioni ERP osservate a livello di siti prefrontali, ed sono particolarmente espresse in termini di ritardo delle latenze. È interessante notare la presenza di meccanismi compensatori negli anziani, riflessi in un aumento nell’ampiezza di diverse componenti (rispetto ai giovani). Ciò suggerisce che l’invecchiamento non solo implica un declino cognitivo e neurale, ma coinvolge anche risposte cognitive e neurali adattive.

2° PARTE: ALTERAZIONI COGNITIVE AND ELETTROFISIOLOGICHE ASSOCIATE ALL’ENCEFALOPATIA EPATICA MINIMA.
L’encefalopatia epatica è una sindrome neuropsichiatrica che può presentarsi in pazienti con cirrosi epatica. Il rilevamento dei primi, seppur lievi, segni dell’encefalopatia epatica è estremamente importante. Questa iniziale e subclinica condizione, chiamata encefalopatia epatica minima (MHE; Ferenci et al., 1998) ha infatti un impatto sulla qualità della vita (Groeneweg et al., 1998; Zhou et al. 2009) e sull’abilità di guida (Wein et al., 2004). Inoltre, ha un valore prognostico negativo in relazione alla probabilità di sviluppare episodi di encefalopatia conclamata, nonché di morte (Amodio et al., 1999; Romero-Gomez et al., 2007). Il profilo della MHE è caratterizzato da alterazioni cognitive che coinvolgono processi quali l’attenzione selettiva, le funzioni esecutive, l’abilità visuo-motoria, la velocità di elaborazione, l’inibizione e la selezione di risposta (Amodio et al., 2005). La MHE causa anche una disfunzione cerebrale comunemente rilevabile sia dal rallentamento dell’elettroencefalogramma (EEG) sia dal ritardo osservato nelle latenze degli ERP, tra cui la P300 (Amodio et al., 2005; Weissenborn et al., 2005). Quindi, quando possibile, la diagnosi di MHE dovrebbe essere preferibilmente basata su una combinazione di indici neuropsicologici/neurofisiologici.
L’Inhibitory Control Task (ICT) è stato recentemente proposto come un semplice strumento diagnostico per la MHE (Bajaj et al. 2007; 2008a). Tuttavia, la sua applicabilità a differenti popolazioni di pazienti con cirrosi, così come la sua relazione con altre misure di MHE necessitano di essere confermate. Per tali motivi, è stato condotto un esperimento (Esperimento 3) che aveva lo scopo di valutare la specificità e la sensibilità dell’ICT per la diagnosi della MHE.
L’Esperimento 4 si è invece focalizzato di indagare l’effetto della MHE sugli ERP elicitati dall’ICT, in modo tale da ottenere informazioni sulle alterazioni cognitive ed elettrofisiologiche caratteristiche della MHE.
A proposito delle alterazioni elettrofisiologiche legate alla MHE, un ulteriore esperimento (Esperimento 5) ha indagato la variabilità intra-individuale dei parametri della P300 (latenza e ampiezza) nei pazienti cirrotici con MHE. C’è un crescente interesse riguardo alla variabilità nella prestazione cognitiva (e.g., nei TR) nel campo delle neuroscienze cognitive (MacDonald et al., 2006) poiché la VII è stata largamente considerata un possibile indice comportamentale di meccanismi neurali compromessi (e.g., Hultsch et al., 2000). Tuttavia gli studi che hanno stabilito un legame tra la VII delle risposte comportamentali e quella delle risposte neurali sono ancora pochi. La MHE sembra un valido modello di patologia per studiare questa relazione poiché i pazienti con MHE mostrano un aumento nella variabilità dei TR (Elsass et al., 1985; Schiff et al., 2006).
Per tale motivo, nell’Esperimento 5, i parametri delle P300 misurati per ogni singola epoca, attraverso la tecnica di stima Bayesiana (D’Avanzo et al., 2011), sono stati esaminati per studiare il correlato elettrofisiologico della VII nella velocità di risposta. Inoltre sono stati esplorati i possibili cambiamenti nella relazione tra i parametri della P300 e dei TR che avvengono in pazienti con MHE.

Esperimenti 3 e 4: L’ICT come strumento adatto per rilevare le alterazioni cognitive ed elettrofisiologiche in pazienti con cirrosi epatica.
Nell’Esperimento 3, 75 pazienti con cirrosi e 55 controlli sani hanno eseguito l’ICT presso due centri di riferimento per lo studio dell’encefalopatia epatica. I pazienti venivano valutati per la MHE attraverso il Psychometric Hepatic Encephalopathy Score (PHES) e le analisi spettrali dell’EEG. La performance alle prove go e nogo è stata comparata tra i due gruppi. I pazienti con cirrosi presentavano un maggior numero di errori (i.e., lures) nelle prove nogo, e mostravano un’accuratezza peggiore anche nelle prove go, rispetto ai controlli. Tuttavia, il numero di lures era comparabile tra pazienti con e pazienti senza MHE. È importante notare come ci fosse una relazione inversa tra accuratezza nelle prove go e numero di errori, quando l’accuratezza nelle prove go era particolarmente bassa. Questo non è sorprendente: una bassa accuratezza alle prove go indica che molte di queste prove avevano una risposta mancante (infatti nelle prove go un errore consiste in una risposta mancante); tuttavia se un individuo commette tante risposte mancanti, allora è più probabile che “esegua” correttamente le prove nogo (le quali infatti prevedono una mancanza di risposta come ‘risposta’ corretta). In questo senso il numero basso di errori alle prove nogo è un fenomeno spurio. È stata quindi codificata una nuova variabile (weighted lures, o “lures pesati”), in cui il numero di lure veniva aggiustato per la percentuale di accuratezza nelle prove go. Tale variabile si è mostrata in grado di differenziare i pazienti con e i pazienti senza MHE. L’accuratezza nelle prove go si è rivelata comunque essere una valida misura anche quando veniva considerata da sola. Quindi, per rilevare segni di MHE, testare l’inibizione (lures) non sembra essere superiore rispetto al testare l’attenzione e l’aggiornamento nella working memory (accuratezza nelle prove go).
L’Esperimento 4 ha permesso di studiare le alterazioni elettrofisiologiche legate alla cirrosi epatica ed evidenziate nelle prove che compongono l’ICT. In tale studio, sono stati analizzati gli ERP confrontando pazienti cirrotici con MHE (N=13), senza MHE (N=18) e individui di controllo (N=17). In particolare sono stati esaminati gli ERP elicitati dalle prove detect, go e nogo, in quanto possono essere un indice dei processi di attenzione selettiva, working memory e inibizione, rispettivamente. I dati sono stati inoltre analizzati attraverso l’analisi PLS, la cui efficacia nell’identificare variabili latenti è particolarmente adatta per dissociare i correlati ERP dei diversi processi. I risultati ottenuti dall’ANOVA e dall’analisi PLS hanno mostrato alterazioni associate alla MHE che interessavano selettivamente gli ERP nelle prove detect. Specificatamente, queste erano rappresentate da una riduzione della P3a a livello di siti frontocentrali e da un ritardo della P3b. Poiché le prove detect coinvolgono principalmente processi attenzionali, le alterazioni evidenziate in tali prove potrebbero indicare un deterioramento delle abilità cognitive più di base, quali l’attenzione. Questo risultato corrobora la conclusione ottenuta nell’esperimento 3, che concerne l’appropriatezza di testare abilità più di base (come l’attenzione) prima, o assieme, alla valutazione delle abilità più di alto livello (i.e., l’inibizione). Il secondo principale, e inaspettato, risultato consiste nell’aumento (invece di una diminuzione) dell’ampiezza di diverse componenti (cioè la N2, la P3-nogo) in pazienti cirrotici senza MHE. Questi cambiamenti elettrofisiologici potrebbero essere un meccanismo compensatorio e riflettere l’allocazione di risorse esecutive addizionali per far fronte alle difficoltà nell’eseguire il compito (anche i pazienti senza MHE mostrano infatti una riduzione nella P3a, indice di deficit attenzionali).

Esperimento 5: La VII della P300 come indice per rilevare disfunzioni neurali in pazienti con cirrosi epatica.
In pazienti con cirrosi, un’aumentata VII dei TR è già stata descritta, ed è stata considerata un possibile indice precoce di disfunzione cerebrale (Schiff et al., 2006). Sfortunatamente, la controparte neurale di questo fenomeno non è stata ancora dimostrata. Tuttavia, siccome una riduzione dell’ampiezza della P300 è stata osservata in questa popolazione di pazienti, allora è possibile ipotizzare che tale riduzione dipenda, almeno in parte, da un’aumentata variabilità delle latenze della P300 tra le singole epoche (come evidenziato per altre patologie, e.g., Hultsch et al., 2000). Per tali motivi, l’aumentata variabilità della P300, se evidenziata, potrebbe essere anch’essa un valido indice di disfunzione neurale. Inoltre, l’analisi della P300 per ogni singola epoca ha permesso di indagare la relazione tra i TR e i parametri (i.e., ampiezza e latenza) della P300, e comprendere come tale relazione cambi nel caso di patologie quali MHE.
L’EEG è stato misurato durante l’esecuzione di un compito di reazione di scelta (compito Simon) in 14 pazienti con MHE (diagnosticata sulla base di test e alterazioni all’EEG), 15 pazienti senza MHE e 14 individui sani di controlli. L’ampiezza e la latenza della P300, assieme alla loro rispettiva deviazione standard, sono state ottenute attraverso un metodo non parametrico di stima bayesiana. La P300 è stata anche misurata con il classico metodo dell’averaging. Infine sono state analizzate la distribuzione dei TR e la sua relazione con i parametri della P300.
Nei pazienti con cirrosi, i TR erano più lenti e più variabili rispetto ai controlli. Un aumento nella variabilità della latenza della P300 è stato anche mostrato in tali pazienti. La regressione lineare multipla ha evidenziato come l’ampiezza della P300 – misurata con il metodo dell’averaging – era predetta sia dalla deviazione standard della latenza della P300, che dalla sua ampiezza (entrambe misurate con il metodo bayesiano). Ciò indica che una ridotta P300 nei pazienti con MHE potrebbe anche dipendere da un’aumentata variabilità nella latenza della stessa.
Inoltre, è stato mostrato come la latenza della P300 aumentava e l’ampiezza diminuiva all’aumentare dei TR nei controlli, ma non nei pazienti con MHE. Un altro segno di alterazione sembra quindi essere la più debole relazione tra parametri comportamentali e la P300, come osservato nei pazienti con MHE.
Riassumendo, il presente studio ha suggerito come in condizioni normali vi sia una stretta relazione tra TR e P300, e la P300 sia stabile tra le diverse prove. In contrasto, quando vi è una disfunzione cerebrale, come nel caso della MHE, la relazione tra i diversi parametri è meno forte, e le risposte neurali diventano più variabili.

2° Parte: Conclusioni
L’utilizzo dell’ICT ha fornito diverse evidenze riguardo ai marker cognitivi e neurali della MHE. Specificatamente, i pazienti con MHE hanno mostrato un rallentamento e un’attenuazione delle componenti della P300 nelle prove detect. Ciò sembra indicare deficit a carico dell’attenzione selettiva e sostenuta. Dall’altra parte, i pazienti senza MHE hanno evidenziato un aumento nelle ampiezze di alcune componenti (N2 e P3-nogo), che potrebbe riflettere un meccanismo neurale compensatorio.
Infine l’esperimento 5 ha evidenziato il profilo della P300 nei pazienti con cirrosi. Infatti, tali pazienti, e specialmente coloro che presentavano MHE, hanno mostrato un aumento nella variabilità della latenza della P300, che può aver contribuito alla riduzione della sua ampiezza.

CONCLUSIONI GENERALI
La tecnica dell’analisi ERP si è rivelata uno strumento utile per esplorare le alterazioni cognitive e neurali sottostanti sia all’invecchiamento sano sia a una condizione patologica, quale la MHE. Sono stati osservati alcuni pattern di alterazioni elettrofisiologiche comuni tra le persone anziane e pazienti con cirrosi epatica (e.g., rallentamento delle componenti ERP, aumento di alcune componenti, quali la N2). Tali alterazioni hanno evidenziato come 1) i deficit legati all’invecchiamento o alla MHE evidenziati in compiti cognitivi complessi sembrano dipendere da alterazioni a carico di meccanismi più di base (come deficit attentivi, o rallentamento nell’elaborazione degli stimoli); 2) l’attività neurale sia di individui anziani sia di pazienti senza MHE è similmente caratterizzata da meccanismi compensatori, reclutati per affrontare le difficoltà nell’eseguire i compiti

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Tipo di EPrint:Tesi di dottorato
Relatore:Bisiacchi, Patrizia S.
Dottorato (corsi e scuole):Ciclo 24 > Scuole 24 > SCIENZE PSICOLOGICHE > PSICOBIOLOGIA
Data di deposito della tesi:26 Gennaio 2012
Anno di Pubblicazione:26 Gennaio 2012
Parole chiave (italiano / inglese):aging, prospective memory, executive control, inhibition, inhibitory control task, ERPs, event-related potentials, minimal hepatic encephalopathy, single-trial analysis,
Settori scientifico-disciplinari MIUR:Area 11 - Scienze storiche, filosofiche, pedagogiche e psicologiche > M-PSI/02 Psicobiologia e psicologia fisiologica
Struttura di riferimento:Dipartimenti > Dipartimento di Psicologia Generale
Codice ID:4540
Depositato il:24 Ott 2012 12:04
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Adrover-Roig, D., & Barcelo, F. (2010). Individual differences in aging and cognitive control modulate the neural indexes of context updating and maintenance during task switching. Cortex, 46, 434–450. Cerca con Google

Alin, A., Kurt, S., McIntosh, A. R., Öniz,A., & Özgören, M. (2009). Partial least squares analysis in electrical brain activity. Journal of Data Science, 7, 99–110. Cerca con Google

Allport, A., & Wylie, G. (2000). Task-switching, stimulus- response bindings, and negative priming. In S. Monsell & J. S. Driver (Eds.), Control of cognitive processes. Attention and performance XVIII. Cambridge, MA: MIT Press. Cerca con Google

Altmann, E.M. (2002). Functional decay of memory for tasks. Psychological Research, 66, 287–297. Cerca con Google

Amodio, P., & Gatta, A. (2005). Neurophysiological investigation of hepatic encephalopathy. Metabolic brain disease, 20(4), 369–79. Cerca con Google

Amodio, P., Campagna, F., Olianas, S., Iannizzi, P., Mapelli, D., Penzo, M., Angeli, P., … Gatta, A. (2008). Detection of minimal hepatic encephalopathy : Normalization and optimization of the Psychometric Hepatic Encephalopathy Score. A neuropsychological and quantified EEG study. Practice, 49, 346–353. Cerca con Google

Amodio, P., Del Piccolo, F., Pettenò, Mapelli, D., Angeli, P., Iemmolo, R., Muraca, M., Musto, C., Gerunda, G., Rizzo, C., Merkel, C., & Gatta, A. (2001). Prevalence and prognostic value of quantified electroencephalogram (EEG) alterations in cirrhotic patients. Journal of Hepatology, 35, 37–45. Cerca con Google

Amodio, P., Marchetti, P., Del Piccolo, F., Beghi, A., Comacchio, F., Carraro, P., Campo, G., Baruzzo, L., Marchiori, C., & Gatta, A. (1997). The effect of flumazenil on subclinical psychometric or neurophysiological alterations in cirrhotic patients: A double-blind placebo-controlled study. Clinical Physiology,17, 533–539. Cerca con Google

Amodio, P., Marchetti, P., Del Piccolo, F., Campo, G., Rizzo, C., Iemmolo, R.M., Gerunda, G., Caregaro, L., Merkel, C., & Gatta, A. (1998a). Visual attention in cirrhotic patients: A study on covert visual attention orienting. Hepatology, 27, 1517–1523. Cerca con Google

Amodio, P., Marchetti, P., Del Piccolo, F., de Tourtchaninoff, M., Varghese, P., Zuliani, C., Campo, G., Gatta, A., & Guerit, J.M. (1999). Spectral versus visual EEG analysis in mild hepatic encephalopathy. Clinical Neurophysiology, 110, 1334–1344. Cerca con Google

Amodio, P., Marchetti, P., Del Piccolo, F., Rizzo, C., Iemmolo, R.M., Caregaro, L., Gerunda, G., & Gatta, A. (1998b). Study on the Sternberg paradigm in cirrhotic patients without overt hepatic encephalopathy. Metabolic Brain Disease,13, 159–172. Cerca con Google

Amodio, P., Montagnese, S., Gatta, A., & Morgan, M. Y. (2004). Characteristics of minimal hepatic encephalopathy. Metabolic brain disease, 19(3-4), 253–267. Cerca con Google

Amodio, P., Quero, J.C., Del Piccolo, F., Gatta, A., & Schalm, S.W. (1996). Diagnostic tools for the detection of subclinical hepatic encephalopathy: Comparison of standard and computerized psychometric tests with spectral-EEG. Metabolic Brain Disease,11, 315–327 Cerca con Google

Amodio, P., Schiff, S., Piccolo, F. D., Mapelli, D., Gatta, A., & Umiltà, C. (2005). Attention Dysfunction in Cirrhotic Patients: An Inquiry on the Role of Executive Control, Attention Orienting and Focusing. Metabolic Brain Disease, 20(2), 115–127. Cerca con Google

Anderson, J.R., & Bower, G.H. (1973). Human Associative Memory. Wiley, New York. Cerca con Google

Andrés, P., Guerrini, C., Phillips, L., & Perfect, T. J. (2008). Differential effects of aging on executive and automatic inhibition. Developmental Neuropsychology, 33(2), 1–23. Cerca con Google

Anguera, J. A., & Gazzaley, A. (2011). Dissociation of motor and sensory inhibition processes in normal aging. Clinical Neurophysiology. International Federation of Clinical Neurophysiology. Cerca con Google

Arias, J.L., Aller, M.-A., Sánchez-Patan, F., & Arias, J. (2006). The inflammatory bases of hepatic encephalopathy. European journal of gastroenterology & hepatology, 18(12), 1297–1310. Cerca con Google

Aron, A.R., 2007. The neural basis of inhibition in cognitive control. The Neuroscientist, 13, 1–15. Cerca con Google

Aron, A.R., Behrens, T.E., Smith, S., Frank, M.J., & Poldrack, R.A. (2007). Triangulating a cognitive control network using diffusion-weighted magnetic resonance imaging (MRI) and functional MRI. Journal of Neuroscience, 27, 3743–3752. Cerca con Google

Backman, L., Almkvist, O., Andersson, J., Nordberg, A., Winblad, B., Reineck, R., & Langstrom, B. (1997). Brain activation in young and older adults during implicit and explicit retrieval. Journal of Cognitive Neuroscience, 9, 378–391. Cerca con Google

Bahn, E., Nolte,W., Kurth, C., Ramadori, G., Ruther, E., & Wiltfang, J. (2002). Quantification of the electroencephalographic theta/alpha ratio for the assessment of portal-systemic encephalopathy following implantation of transjugular intrahepatic portosystemic stent shunt (TIPSS). Metabolic Brain Disease,17,19–28. Cerca con Google

Bajaj, J. S., Hafeezullah, M., Franco, J., Varma, R. R., Hoffmann, R. G., Knox, J. F., Hischke, D., et al. (2008a). Inhibitory control test for the diagnosis of minimal hepatic encephalopathy. Gastroenterology, 135(5), 1591–1600. Cerca con Google

Bajaj, J. S., Hafeezullah, M., Hoffmann, R. G., Varma, R. R., Franco, J., Binion, D. G., Hammeke, T. A. & Saeian, K. (2008b), Navigation skill impairment: Another dimension of the driving difficulties in minimal hepatic encephalopathy. Hepatology, 47, 596–604. Cerca con Google

Bajaj, J. S., Hafeezullah, M., Hoffmann, R. G., Varma, R. R., Franco, J., Binion, D. G., Hammeke, T. A. & Saeian, K. (2008b), Navigation skill impairment: Another dimension of the driving difficulties in minimal hepatic encephalopathy. Hepatology, 47, 596–604. Cerca con Google

Bajaj, J. S., Saeian, K., Verber, M. D., Hischke, D., Hoffmann, R. G., Franco, J., Varma, R. R., et al. (2007). Inhibitory control test is a simple method to diagnose minimal hepatic encephalopathy and predict development of overt hepatic encephalopathy. The American journal of gastroenterology, 102(4), 754–60. Cerca con Google

Bajaj, J. S., Schubert, C. M., Heuman, D. M., Wade, J. B., Gibson, D. P., Topaz, A., Saeian, K., Heuman, D.M., Wade, J.B., Hafeezullah, M., Bell, D.E., Sterling, R.K., Stravitz, R.T, Luketic, V., White, M.B., & Sanyal., A.J. (2010). Persistence of cognitive impairment after resolution of overt hepatic encephalopathy. Gastroenterology, 138(7), 2332-40. Cerca con Google

Bajaj, J. S., Wade, J. B., & Sanyal, A. J. (2009). Spectrum of neurocognitive impairment in cirrhosis: Implications for the assessment of hepatic encephalopathy. Hepatology, 50(6), 2014–21. Cerca con Google

Bajaj, J.S., Hafeezullah, M., Franco, J., Joshua, F.K, Varma, R.R, Hammeke, T.A., Pinkerton, S., Hoffmann, R.G., & Saeian, K. (2008a). Inhibitory control test for the diagnosis of minimal hepatic encephalopathy. Gastroenterology, 135, 1591–1600. Cerca con Google

Balota, D.A. & Yap, M.J. (2011). Moving Beyond the Mean in Studies of Mental Chronometry: The Power of Response Time Distributional Analyses. Current directions in Psychological Science, 20, 160-166. Cerca con Google

Baltes, P. B., & Lindenberger, U. (1997). Emergence of a powerful connection between sensory and cognitive functions across the adult life span: A new window to the study of cognitive aging? Psychology and Aging, 12(1), 12–21. Cerca con Google

Baltes, P. B., & Smith, J. (1997). A systemic-wholistic view of psychological functioning in very old age: Introduction to a collection of articles form the Berlin Aging Study. Psychology and Aging, 12, 395–409. Cerca con Google

Baltes, P. B., Staudinger, U. M., Maercker, A. & Smith, J. (1995). People nominated as wise: a comparative study of wisdom-related knowledge. Psychology of Aging, 10, 155–166. Cerca con Google

Barceló, F. (2003). The Madrid Card Sorting Test (MCST): A task switching paradigm to study executive attention with event-related potentials. Brain Research Protocols, 11(1), 27–37. Cerca con Google

Barceló, F., Perianez, J. A., & Knight, R. T. (2002). Think differently: A brain orienting response to task novelty. NeuroReport, 13(15), 1887–1892. Cerca con Google

Bargh, J.A., & Chartrand, T.L. (1999). The unbearable automaticity of being. American Psychology. 54, 462–479. Cerca con Google

Barrett, G., Neshige. R., & Shibasaki, H. (1987). Human auditory and somatosensory event-related potentials: effects of response condition and age. Electroencephalography and clinical Neurophysiology, 66(4), 409–419. Cerca con Google

Bastin, C., & Meulemans, T. (2002). Are time-based and event-based prospective memory affected by normal aging in the same way? Current Psychology Letters: Behaviour, Brain & Cognition, 7, 105–121. Cerca con Google

Bäumler, G. (1974). Lern-und Gedaechtnistes (LGT-3): Handanweisung. Hogrefe, Goettingen, Germany. Cerca con Google

Bedard, A C., Nichols, S., Barbosa, J. A., Schachar, R., Logan, G. D., & Tannock, R. (2002). The development of selective inhibitory control across the life span. Developmental Neuropsychology, 21, 93–111. Cerca con Google

Bellgrove, M.A., Hester, R., & Garavan, H. (2004). The functional neuroanatomical correlates of response variability: evidence from a response inhibition task. Neuropsychologia, 42, 1910- 1916. Cerca con Google

Benjamini, Y., & Hochberg, Y. (1995). Controlling the False Discovery Rate: A Practical And Powerful Approach to Multiple testing. Journal of the Royal Statistical Society. B, 57(1), 289-300. Cerca con Google

Benjamini, Y., & Yekutieli, D. (2001). The control of the false discovery rate in multiple testing under dependency, Annals of Statistics 29, 1165–1188. Cerca con Google

Berti, S. (2008a). Cognitive control after distraction: event-related brain potentials (ERPs) dissociate between different processes of attentional allocation. Psychophysiology, 45(4), 608–620. Cerca con Google

Berti, S. (2008b). Object switching within working memory is reflected in the human event-related brain potential. Neuroscience letters, 434(2), 200–5. Cerca con Google

Berti, S., & Schroger, E. (2001). A comparison of auditory and visual distraction effects: behavioral and event-related indices. Cognitive Brain Research, 10, 265–273. Cerca con Google

Berti, S., & Schröger, E., (2003). Working memory controls involuntary attention switching: evidence from an auditory distraction paradigm. European Journal of Neuroscience, 17, 1119–1122. Cerca con Google

Berti, S., Roeber, U., & Schröger, E., (2004). Bottom-up influences on working memory: behavioral and electrophysiological distraction varies with distractor strength. Experimental Psychology, 51, 249–257. Cerca con Google

Beste, C., Willemssen, R., Saft, C., & Falkenstein, M. (2009). Error processing in normal aging and in basal ganglia disorders. Neuroscience, 159, 143–149. Cerca con Google

Beste, C., Willemssen, R., Saft, C., & Falkenstein, M. (2010). Neuropsychologia Response inhibition subprocesses and dopaminergic pathways : Basal ganglia disease effects. Neuropsychologia, 48, 366–373. Cerca con Google

Bisiacchi, P. S. (1996). The neuropsychological approach in the study of prospective memory. In M. Brandimonte, G. O. Einstein, & M. A. McDaniel (Eds.), Prospective memory: Theory and applications. Mahwah, NJ: Lawrence Erlbaum Associates. 297–317. Cerca con Google

Bisiacchi, P. S., Cona, G., Schiff, S., & Basso, D. (2011). Modulation of a fronto-parietal network in event-based prospective memory: An rTMS study. Neuropsychologia, 49, 2225–2232. Cerca con Google

Bisiacchi, P. S., Schiff, S., Ciccola, A., & Kliegel, M. (2009). The role of dual-task and task-switch in prospective memory: Behavioural data and neural correlates. Neuropsychologia, 47, 1362 – 1373. Cerca con Google

Bisiacchi, P. S., Tarantino, V., & Ciccola, A. (2007). Aging and prospective memory : the role of working memory and monitoring processes. Aging, 20(6), 569–577. Cerca con Google

Botvinick, M. M., Braver, T. S., Barch, D. M., Carter, C. S., & Cohen, J. D. (2001). Conflict monitoring and cognitive control. Psychological Review, 108(3), 624–652. Cerca con Google

Brandimonte, M. A., Einstein, G. O., & McDaniel, M. A. (1996). Prospective memory: Theory and applications. Mahwah, NJ: Erlbaum. Cerca con Google

Braver, T. S., & Barch, D. M. (2002). A theory of cognitive control, aging cognition, and neuromodulation. Neuroscience and biobehavioral reviews, 26(7), 809–17. Cerca con Google

Braver, T. S., Barch, D.M., Keys, B. A., Carter, C. S., Cohen, J. D., Kaye, J. A. … Reed, B. (2001). Context processing in older adults: Evidence for a theory relating cognitive control to neurobiology in healthy aging. Journal of Experimental Psychology: General, 130, 746–763. Cerca con Google

Braver, T. S., Cohen, J. D., & Barch, D. M. (2002). The role of the prefrontal cortex in normal and disordered cognitive control: A cognitive neuroscience perspective. In D. T. Stuss & R. T. Knight (Eds.), Principles of frontal lobe function (pp. 428–448). Oxford, England: Oxford University Press. Cerca con Google

Braver, T. S., Gray, J. R., & Burgess, G. C. (2007). Explaining the many varieties of working memory variation: Dual mechanisms of cognitive control. In A. Conway, C. Jarrold, M. Kane, A. Miyake & J. Towse (Eds.), Variation in working memory. Oxford, England: Oxford University Press. Cerca con Google

Braver, T. S., Paxton, J. L., Locke, H. S., & Barch, D. M. (2009). Flexible neural mechanisms of cognitive control within human prefrontal cortex. Proceedings of the National Academy of Sciences of the United States of America, 106(18), 7351–6. Cerca con Google

Braver, T.S., & West, R. (2008). Working memory, executive control, and aging. In F. I. Craik & T. Salthouse (Eds.), The handbook of aging and cognition (3rd ed, pp. 311–372). New York, NY: Psychology Press. Cerca con Google

Braver, T.S., Satpute, A.B., Keys, B.A., Racine, C.A., & Barch, D.M. (2005). Context processing and context maintenance in healthy aging and early- stage dementia of the Alzheimer’s type. Psychology and Aging, 20, 33–46. Cerca con Google

Brikenkamp, R. (1981). Test d2.Aufmerksamkeits-Belastungs-Test.Verlag fur Psychologie Hogrefe, Goettingen-Toronto-Zurich. Cerca con Google

Brown, W.S., Marsh, J.T., & LaRue, A. (1983). Exponential electrophysiological aging: P3 latency. Electroencephalography and clinical Neurophysiology, 55(3), 277–285. Cerca con Google

Buchner, A., & Mayr, S. (2004). Auditory negative priming in younger and older adults. The Quarterly Journal of Experimental Psychology, 57A, 769–787. Cerca con Google

Bunting, M. (2006). Proactive interference and item similarity in working memory. Journal of Experimental Psychology: Learning, Memory, and Cognition, 32, 183–196. Cerca con Google

Burgess, P. W., & Shallice, T. (1997). The relationship between prospective and retrospective memory: Neuropsychological evidence. in M. A. Conway (ed.), Cognitive models of memory (pp. 247–272). Cambridge, Ma: Mit Press. Cerca con Google

Burgess, P. W., Dumontheil,I., Gilbert, S., Okuda,J., Schölvinck, M., & Simons, J. (2008). On the role of rostral prefrontal cortex (area 10) in prospective memory. In M. Kliegel, M. A. McDaniel, & G. O. Einstein (Eds.), Prospective memory: Cognitive, neuroscience, developmental, and applied perspectives. Mahwah: Erlbaum. Cerca con Google

Burgess, P.W., Gonen-Yaacovi, G., & Volle, E. (2011). Functional neuroimaging studies of prospective memory: What have we learnt so far? Neuropsychologia, 49, 2246–2257. Cerca con Google

Burton, C.L., Hultsch, D.F., Strauss, E., & Hunter, M.A. (2002). Intraindividual variability in physical and emotional functioning: comparison of adults with traumatic brain injuries and healthy adults. Clinical Neuropsychology, 16, 264–279. Cerca con Google

Bustamante J, Rimola A, Ventura PJ, Navasa M, Cirera I, Reggiardo V, et al. (1999) Prognostic significance of hepatic encephalopathy in patients with cirrhosis. Journal of Hepatology, 30, 890–895. Cerca con Google

Butler, K. M., Zacks, R. T., & Henderson, J. M. (1999). Suppression of reflexive saccades in younger and older adults: Age comparisons on an antisaccade task. Memory & Cognition, 27, 584–591. Cerca con Google

Butterworth RF. (1996). The neurobiology of hepatic encephalopathy. Seminars in Liver Diseases, 16, 235–244. Cerca con Google

Butterworth, R. F. (2000). Complications of cirrhosis III. Hepatic encephalopathy. Journal of Hepatology, 32(1 Suppl), 171– 80. Cerca con Google

Cabeza, R. (2002) Hemispheric asymmetry reduction in old adults: the HAROLD model. Psychology of Aging. 17, 85–100. Cerca con Google

Cabeza, R., Anderson, N. D., Locantore, J. K., & McIntosh, A. R. (2002). Aging gracefully: Compensatory brain activity in high-performing older adults. NeuroImage, 17(3), 1394-1402. Cerca con Google

Cabeza, R., Daselaar, S. M., Dolcos, F., Prince, S. E., Budde, M., & Nyberg, L. (2004). Task- independent and task-specific age effects on brain activity during working memory, visual attention and episodic retrieval. Cerebral Cortex, 14(4), 364–375. Cerca con Google

Cabeza, R., Grady, C. L., Nyberg, L., McIntosh, A. R., Tulving, E., Kapur, S., et al. (1997). Age- related differences in neural activity during memory encoding and retrieval: A positron emission tomography study. Journal of Neuroscience, 17(1), 391–400. Cerca con Google

Carlson, M. C., Hasher, L., Connelly, S. L., & Zacks, R. T. (1995). Aging, distraction, and the benefits of predictable location. Psychology and Aging, 10, 427–436. Cerca con Google

Casellas, F., Sagalés, T., de la Calzada, M.D., Accarino, A., Vargas, V., & Guarner, L. (1985). Visual evoked potentials in hepatic encephalopathy. Lancet, 325, 394–395. Cerca con Google

Castellanos, F.X., Sonuga-Barke, E.J., Milham, M.P., & Tannock, R. (2006). Characterizing cognition in ADHD: beyond executive dysfunction. Trends in Cognitive Science, 10, 117–123. Cerca con Google

Castellanos, F.X., Sonuga-Barke, E.J., Scheres, A., Di, M.A., Hyde, C., & Walters, J.R. (2005). Varieties of attention-deficit/hyperactivity disorder-related intra-individual variability. Biological Psychiatry, 57, 1416–1423. Cerca con Google

Cerella, J. (1985). Information processing rates in the elderly. Psychological Bulletin, 1, 67–83. Cerca con Google

Chambers, C. D., Garavan, H., & Bellgrove, M. A. (2009). Neuroscience and Biobehavioral Reviews: Insights into the neural basis of response inhibition from cognitive and clinical neuroscience. Biobehavioral Reviews, 33, 631–646. Cerca con Google

Chambers, C.D., Bellgrove, M.A., Stokes, M.G., Henderson, T.R., Garavan, H., Robertson, I.H., Morris, A.P., & Mattingley, J.B. (2006). Executive ‘brake failure’ following deactivation of human frontal lobe. Journal of Cognitive Neuroscience, 18, 444– 455. Cerca con Google

Chen, Y., Huang, X., Jackson, T., & Yang, H. (2009). Effect of characteristics of target cues on task interference from prospective memory. NeuroReport, 20, 81–86. Cerca con Google

Chen, Y., Huang, X., Ren, G., Chen, Y., & Yue, C. (2007). Task interference from event-based prospective memory : an event-related potentials study, NeuroReport, 18, 1951–1955. Cerca con Google

Cherry, K. E., & Le Compte, D. C. (1999). Age and individual differences influence prospective memory. Psychology and Aging, 14, 60–76. Cerca con Google

Cherry, K. E., Martin, R. C., Simmons-D’Gerolamo, S. S., Pinkston, J. B., Griffing, A., & Gouvier, W. D. (2001). Prospective remembering in younger and older adults: role of the prospective cue. Memory, 9, 177–193. Cerca con Google

Cherry, K.E., & Park, D.C. (1993).Individual differenced and contextual variables influence spatial memory in younger and older adults. Psychology and Aging, 8, 517–526. Cerca con Google

Chiappe, P., Hasher, L., & Siegel, L. S. (2000). Working memory, inhibitory control, and reading disability. Memory & Cognition, 28, 8–17. Cerca con Google

Christensen, H., Dear, K.B., Anstey, K.J., Parslow, R.A., Sachdev, P., & Jorm, A.F. (2005). Within- occasion intraindividual variability and preclinical diagnostic status: is intraindividual variability an indicator of mild cognitive impairment? Neuropsychology, 19, 309–317. Cerca con Google

Chu, N.S., & Yang, S.S. (1988). Portal-systemic encephalopathy: Alterations in somatosensory and brainstem auditory evoked potentials. Journal of the Neurological Sciences, 84, 41–50. Cerca con Google

Chu, N.S., Yang, S.S., & Liaw, Y.F. (1997). Evoked potentials in liver diseases. Journal of Gastroenterology and Hepatology, 12, S288–S293. Cerca con Google

Ciancio, A., Marchet, A., Saracco, G., Carucci, P., Lavezzo, B., Leotta, D., Capellero, B., Nobili, M., Smedile, A., & Rizzetto, M. (2002). Spectral electroencephalogram analysis in hepatic encephalopathy and liver transplantation. Liver Transplantation journal, 8, 630–635. Cerca con Google

Cockburn, J., & Smith, P. T. (1988). Effects of age and intelligence on everyday memory tasks. In M. M. Gruneberg, P. E. Morris, & R. N. Sykes (Eds.), Practical aspects of memory: Current research and issues. Vol. 2: Clinical and educational implications (pp. 132-136). Chichester, U.K.: Wiley. Cerca con Google

Cohen, A. L., West, R., & Craik, F. I. M. (2001). Modulation of the prospective and retrospective components of memory for intentions in younger and older adults. Aging, Neuropsychology and Cognition, 8, 1–13. Cerca con Google

Cohen, J. D., Dunbar, K., & McClelland, J. L. (1990). On the control of automatic processes: A parallel distributed processing account of the Stroop effect. Psychological Review, 97, 332–361. Cerca con Google

Cohen, J.D., Braver, T.S., O’Reilly, R. (1996). A computational approach to prefrontal cortex, cognitive control, and schizophrenia: recent developments and current challenges. Philosophical Transactions of the Royal Society B: Biological Sciences, 351, 1515–1527. Cerca con Google

Collette, F., Germain, S., Hogge, M., & Van der Linden, M. (2009). Inhibitory control of memory in normal ageing: dissociation between impaired intentional and preserved unintentional processes. Memory, 17(1), 104–22. Cerca con Google

Cona, G., Arcara, G., Tarantino V., & Bisiacchi, P.S (in press). Electrophysiological correlates of strategic monitoring in event-based and time-based prospective memory. PLoSONE. Cerca con Google

Conn, H.O., Leevy, C.M., Vlahcevic, Z.R., Rodgers, J.B., Maddrey, W.C., Seeff, L., & Levy, L.L. (1977). Comparison of lactulose and neomycin in the treatment of chronic portal-systemic encephalopathy. A double blind controlled trial. Gastroenterology, 72, 573–583. Cerca con Google

Connelly, S. L., & Hasher, L. (1993). Aging and the inhibition of spatial location. Journal of Experimental Psychology: Human Perception and Performance, 19, 1238–1250. Cerca con Google

Costa, A., Oliveri, M., Barban, F., Torriero, S., Salerno, S., Lo Gerfo, E., Koch, G., et al. (2011). Keeping Memory for Intentions: A cTBS Investigation of the Frontopolar Cortex. Cerebral cortex, 1-8. Cerca con Google

Cowan, N. (1995). Attention and memory: An integrated framework. Oxford University Press: New York. Cerca con Google

Cowan, N. (1999). An embedded-processes model of working memory. In: Miyake, A., Shah, P. (Eds.), Models of working memory: mechanisms of active maintenance and executive control. Cambridge University Press, Cambridge, pp. 62–101. Cerca con Google

Cowan, N. (2001) The magical number 4 in short-term memory: A reconsideration of mental storage capacity. Behavioural Brain Science, 24, 87–185 Cerca con Google

Craik, F. I. M. (1983). On the transfer of information from temporary to permanent memory. Philosophical Transactions of the Royal Society, London, Series B, 302, 341–359. Cerca con Google

Craik, F. I. M., & Bosman, E. A. (1992). Age-related changes in memory and learning. In H. Bouma & J. Graafmans (Eds.), Gerontechnology: Proceedings of the First International Conference on Technology and Aging (pp. 79–92). Eindhoven: IOS Press Cerca con Google

Craik, F. I. M., & Byrd, M. (1982). Aging and cognitive deficits: The role of attentional resources. In F. I. M. Craik & S. Trehub (Eds.), Aging & Cognitive Processes: Advances in the Study of Communication and Affect (Vol. 8, pp. 191-211). New York: Plenum Press. Cerca con Google

Craik, F.I.M. (1986). A functional account of age differences in memory. In: F. Clix & H. Hangendorf (eds.) Human Memory and Cognitive Capabilities: Mechanisms and Performances, pp. 409–422. Amsterdam: Elsevier. Cerca con Google

D’Avanzo, C., Schiff, S., Amodio, P., & Sparacino, G. (2011). A Bayesian method to estimate single- trial event-related potentials with application to the study of the P300 variability. Journal of Neuroscience Method. 198, 114–124. Cerca con Google

d’Ydewalle, G. (1995). Age-related interference of intervening activities in a prospective memory task. Psychologica Belgica, 35, 189–203. Cerca con Google

d’Ydewalle, G., & Brunfaut, E. (1996). Are older subjects necessarily worse in prospective memory tasks? In M. Georgas, E. Manthouli, E. Besevegis, & A. Kokkevi (Eds.), Contemporary psychology in Europe: Theory, research and applications (pp. 161–172). Gottingen, Germany: Hogrefe & Huber. Cerca con Google

d’Ydewalle, G., Bouckaert, D., & Brunfaut, E. (2001). Age-related differences and complexity of ongoing activities in time- and event-based prospective memory. American Journal of Psychology, 114, 411–423. Cerca con Google

d’Ydewalle, G., Luwel, K., & Brunfaut, E. (1999). The importance of on-going concurrent activities as a function of age in time- and event- based prospective memory. European Journal of Cognitive Psychology, 11, 219–237. Cerca con Google

Daffner, K. R., Chong, H., Sun, X., Tarbi, E. C., Riis, J. L., McGinnis, S. M., & Holcomb, P. J. (2011). Mechanisms underlying age- and performance-related differences in working memory. Journal of cognitive neuroscience, 23(6), 1298–314. Cerca con Google

Daffner, K. R., Rentz, D., Scinto, L. F. M., Faust, R., Budson, A. E., & Holcomb, P. J. (2001). Pathophysiology underlying diminished attention to novel events in patients with early AD. Neurology, 56, 1377–1383. Cerca con Google

Daffner, K. R., Ryan, K. K., Williams, D. M., Budson, A. E., Rentz, D. M., Wolk, D. A, & Holcomb, P. J. (2006). Increased responsiveness to novelty is associated with successful cognitive aging. Journal of cognitive neuroscience, 18(10), 1759–73. Cerca con Google

Daffner, K.R., Mesulam, M.M., Scinto, L.F.M., Cohen, L.G., Kennedy, B.P., West, W.C., & Holcomb, P.J. (1998). Regulation of attention to novel stimuli by frontal lobes: an event-related potential study. NeuroReport, 9, 787–791. Cerca con Google

Damoiseaux, J. S., Beckmann, C. F., Arigita, E., Barkhof, F., Scheltens, P., Stam, C. J., & Rombouts, S. B. (2008). Reduced resting-state brain activity in the “default network” in normal aging. Cerebral Cortex, 18, 1856–1864. Cerca con Google

Daselaar, S. M., & Cabeza, R. (2005). Age-related changes in hemispheric organization. In R. Cabeza, L. Nyberg, & D. Park (Eds.), Cognitive neuroscience of aging (pp. 325–353). Oxford: Oxford University Press. Cerca con Google

Davis, S. W., Dennis, N. A., Daselaar, S. M., Fleck, M. S., & Cabeza, R. (2007). Que PASA? The posterior anterior shift in aging. Cerebral Cortex, 18, 1201–1209. Cerca con Google

De Beni, R., & Palladino, P. (2004). Decline in working memory updating through ageing: Intrusion error analyses. Memory, 12, 75–89. Cerca con Google

De Frias, C. M., Dixon, R. A., & Strauss, E. (2009). Characterizing executive functioning in older special populations: From cognitively elite to cognitively impaired. Neuropsychology, 23, 778–791. Cerca con Google

De Frias, C. M., Dixon, R. F., & Strauss, E. (2006). Structure of four executive functioning tests in healthy older adults. Neuropsychology, 20, 206–214. Cerca con Google

De Jong, R., Liang, C.C., & Lauber, E. (1994). Conditional and unconditional automaticity: a dual- process model of effects of spatial stimulus-response correspondence. Journal of Experimental Psychology, 20, 731–750. Cerca con Google

De Jong, R., Wierda, M., Mulder, G., & Mulder, L.J.M., (1988). Use of partial stimulus information in response processing. Journal of Experimental Psychology, 14, 682–692. Cerca con Google

De Lucia, M., Michel, C.M., & Murray, M.M. (2010) Comparing ICA-based and Single-Trial Topographic ERP Analyses. Brain Topography, 23, 119–127. Cerca con Google

Delorme, A., & Makeig, S. (2004) EEGLAB: an open source toolbox for analysis of single-trial EEG dynamics including independent component analysis. Journal of Neuroscience Methods, 134, 9–21. Cerca con Google

Dempster, F.N. (1991). Inhibitory processes: a neglected dimension of intelligence. Intelligence, 15, 157–73. Cerca con Google

Development Core Team (2011). R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. ISBN 3-900051-07-0, http://www.R- project.org Vai! Cerca con Google

Devolder, P. A., Brigham, M. C., & Pressley, M. (1990). Memory performance awareness in younger and older adults. Psychology and Aging, 5, 291–303. Cerca con Google

Dhiman RK, & Chawla YK. (2009). Minimal hepatic encephalopathy. Indian Journal of Gastroenterology, 28, 5–16. Cerca con Google

Dillon, D.G., & Pizzagalli, D.A. (2007). Inhibition of action, thought, and emotion: a selective neurobiological review. Applied and Preventive Psychology, 12, 99–114. Cerca con Google

Dimoska, A., Johnstone, S.J., Barry, R.J., & Clarke, A. (2003). Inhibitory motor control in children with Attention-deficit/Hyperactivity Disorder: Event-related potentials in the stop-signal paradigm. Biological Psychiatry, 54, 1340–1349. Cerca con Google

Dobbs, A.R., & Rule, B.G. (1987). Prospective memory and self-reports of memory abilities in older adults. Canadian Journal of Psychology, 41, 209–222. Cerca con Google

Donchin, E., & Coles, M. G. (1988). Is the P300 component a manifestation of context updating? Behavioral and Brain Sciences, 11, 357–427. Cerca con Google

Donkers, F.C.L., & Van Boxtel, G.J.M., (2004). The N2 in go/nogo tasks reflects conflict monitoring not response inhibition. Brain Cognition, 56, 165–176. Cerca con Google

Duarte, A., Ranganath, C., Trujillo, C., & Knight, R.T. (2006). Intact recollection memory in high-performing older adults: ERP and behavioral evidence. Journal of Cognitive Neuroscience, 18, 33–47. Cerca con Google

Eimer M. (1996). The N2pc component as an indicator of attentional selectivity. Electroencephalography and Clinical Neurophysiology 99, 225–34. Cerca con Google

Eimer, M. (1993). Effects of attention and stimulus probability on ERPs in a go/no-go task. Biological Psychology, 35, 123–138. Cerca con Google

Eimer, M., & Schlaghecken, F. (1998). Effects of masked stimuli on motor activation: behavioral and electrophysiological evidence. Journal of Experimental Psychology: Human Perception and Performance, 24, 1737–1747. Cerca con Google

Einstein, G. O., & McDaniel, M. A. (1990). Normal aging and prospective memory. Journal of Experimental Psychology: Learning, Memory, and Cognition, 16, 717–726. Cerca con Google

Einstein, G. O., & McDaniel, M. A. (1996). Retrieval processes in prospective memory: Theoretical approaches and some new empirical findings. In M. Brandimonte, G. O. Einstein, & M. A. McDaniel (Eds.), Prospective memory: Theory and applications (pp. 115–142). Hillsdale, NJ: Erlbaum. Cerca con Google

Einstein, G. O., Holland, L. J., McDaniel, M. A., & Guynn, M. J. (1992). Age-related deficits in prospective memory: The influence of task complexity. Psychology and Aging, 7, 471–478. Cerca con Google

Einstein, G. O., McDaniel, M. A., Manzi, M., Cochran, B., & Baker, M. (2000). Prospective Memory and Aging: Forgetting Intentions Over Short Delays. Psychology and Aging, 15(4), 1–13. Cerca con Google

Einstein, G. O., McDaniel, M. A., Richardson, S. L., Guynn, M. J., & Cunfer, A. R. (1995). Aging and prospective memory: Examining the influences of self-initiated retrieval processes. Journal of Experimental Psychology: Learning, Memory, and Cognition, 21, 996–1007. Cerca con Google

Ellis, J. (1996). Prospective memory or the realization of delayed intentions: A conceptual framework for research. In M. Brandimonte, G. O. Einstein, & M. A. McDaniel (Eds.), Prospective memory: Theory and applications (pp. 1–22). Mahwah, NJ: Erlbaum. Cerca con Google

Ellis, J., & Milne, A. (1996). Retrieval cue specificity and the realization of delayed intentions. Quarterly Journal of Experimental Psychology, 49, 862–887. Cerca con Google

Ellis, J., Kvavilashvili, L., & Milne, A. (1999). Experimental tests of prospective remembering: The influence of cue-event frequency on performance. British Journal of Psychology, 90, 9–23. Cerca con Google

Elsass, P., Christensen, S.E., Mortensen, E.L., & Vilstrup, H. (1985). Discrimination between organic and hepatic encephalopathy by means of continuous reaction times. Liver, 5, 29–34. Cerca con Google

Elsass, P., Lund, Y., & Ranek, L. (1978). Encephalopathy in patients with cirrhosis of the liver. A neuropsychological study. Scandinavian Journal of Gastroenterology, 13, 241–247. Cerca con Google

Eppinger, B., Kray, J., Mecklinger, A., & John, O. (2007). Age difference in task switching and response monitoring: Evidence from ERPs. Biological Psychology, 75, 52–67. Cerca con Google

Eriksen, B. A., & Eriksen, C. W. (1974). Effects of noise letters upon the identification of a target letter in a nonsearch task. Perception & Psychophysics, 16, 143–149. Cerca con Google

Escera, C., Alho, K., Schröger, E., & Winkler, I., (2000). Involuntary attention and distractibility as evaluated with event-related brain potentials. Audiology and Neurootology, 5, 151–166. Cerca con Google

Escera, C., Yago, E., & Alho, K. (2001). Electrical responses reveal the temporal dynamics of brain events during involuntary attention switching. European Journal of Neuroscience, 14, 877–883. Cerca con Google

Falkenstein, M., Hoormann, J., & Hohnsbein, J. (1999). ERP components in go/nogo tasks and their relation to inhibition. Acta Psychologica, 101, 267–291. Cerca con Google

Falkenstein, M., Hoormann, J., & Hohnsbein, J. (2001). Changes of error- related ERPs with age. Experimental Brain Research, 138, 258–262. Cerca con Google

Falkenstein, M., Hoormann, J., & Hohnsbein, J. (2002). Inhibition-related ERP components: Variation with modality, age, and time-on-task. Journal of Psychophysiology, 16(3), 167–175. Cerca con Google

Falkenstein,M., Koshlykova, N. A., Kiroj, V. N., Hoormann, J., & Hohnsbein, J. (1995). Late ERP components in visual and auditory go/nogo tasks. Electroencephalography and Clinical Neurophysiology, 96, 36–43. Cerca con Google

Fallgatter, A. J., Mueller, T. J., & Strik,W. K. (1999). Age-related changes in the brain electrical correlates of response control. Clinical Neurophysiology, 110, 833–838. Cerca con Google

Fassbender, C., Zhang, H., Buzy, W.M., Cortes, C.R., Mizuiri, D., Beckett, L., & Schweitzer, J.B. (2009). A lack of default network suppression is linked to increased distractibility in ADHD. Brain Research, 1273, 114–128. Cerca con Google

Fein, G., & Turetsky, B. (1989). P300 latency variability in normal elderly: Effects of paradigm and measurement technique. Electroencephalography and Clinical Neurophysiology, 72, 384–394. Cerca con Google

Felipo, V., Ordoño, J.F., Urios, A., Mlili, N.E., Giménez- Garzó, C., Aguado, C., … Montoliu, C. (in press). Patients with minimal hepatic encephalopathy show impaired mismatch negativity correlating with reduced performance in attention tests. Hepatology. DOI: 10.1002/hep.24704. Cerca con Google

Fell, J. (2007). Cognitive neurophysiology: beyond averaging. Neuroimage, 37, 1069–1072. Cerca con Google

Ferenci,P., Lockwood, A., Mullen, K.,Tarter,R.,Weissenborn, K., & Blei, A.T. (2002).Hepatic encephalopathy– definition, nomenclature, diagnosis, and quantification: Final report of the working party at the 11th World Congresses of Gastroenterology, Vienna, 1998. Hepatology, 35, 716–721. Cerca con Google

Fernandez-Duque, D., & Black, S. E. (2006). Attentional networks in normal aging and Alzheimer’s disease. Neuropsychology, 20, 133–143. Cerca con Google

Fisk, J.E., & Sharp, C.A. (2004). Age-related impairment in executive functioning: Updating, inhibition, shifting, and access. Journal of Clinical and Experimental Neuropsychology, 26, 874–890. Cerca con Google

Fjell, A. M., & Walhovd, K. B. (2001). P300 and neuropsychological tests as measures of aging: Scalp topography and cognitive changes. Brain Topography, 14, 25–40. Cerca con Google

Fjell, A.M., Rosquist, H., & Walhovd, K.B. (2009). Instability in the latency of P3a/P3b brain potentials and cognitive function in aging. Neurobiology of Aging, 30, 2065–2079. Cerca con Google

Fogelson, N., Shah, M., Bonnet-Brilhault, F., & Knight, R. (2010). Electrophysiological evidence for aging effects on local contextual processing, Cortex, 46(4), 498–506. Cerca con Google

Folstein, F., Folstein, S.E., & McHugh, P.R. (1975). “Mini-mental state”: A practical method for grading the cognitive state of patients for the clinician, Journal of Psychiatric Research, 12(3), 189–198. Cerca con Google

Folstein, J. R., & Van Petten, C. (2008). Influence of cognitive control and mismatch on the N2 component of the ERP: a review. Psychophysiology, 45(1), 152–70. Cerca con Google

Forstmann, B.U., van den Wildenberg, W.P.M., & Ridderinkhof, K.R. (2008). Neural Mechanisms, Temporal Dynamics, and Individual Differences in Interference Control. Journal of Cognitive Neuroscience, 20, 1854–1865. Cerca con Google

Friedman, D. & Simpson, G. (1994). Amplitude and scalp distribution of target and novel events: effects of temporal order in young, middle-aged and older adults. Cognitive Brain Research, 2, 49–63. Cerca con Google

Friedman, D., Cycowicz, Y.M., & Gaeta, H., (2001). The novelty P3: an event- related brain potential (ERP) sign of the brain’s evaluation of novelty. Neuroscience Biobehavioural Review. 25, 355–373 Cerca con Google

Friedman, D., Nessler, D., Johnson, R., Ritter, W., & Bersick, M. (2008). Age-related changes in executive function: an event- related potential (ERP) investigation of task-switching. Neuropsychology, development, and cognition, Section B: Aging, 15, 95–128. Cerca con Google

Friedman, N. P., & Miyake, A. (2004). The relations among inhibition and interference control functions: A latent-variable analysis. Journal of Experimental Psychology: General, 133, 101–135. Cerca con Google

Fristoe, N. M., Salthouse, T. A., & Woodward, J. L. (1997). Examination of age-related deficits on the Wisconsin Card Sorting Test. Neuropsychology, 11, 428–436. Cerca con Google

Funke, J., & Krüger, T. (1993). Plan-A-Day (PAD). Bonn, Germany: Psychologisches institut der Universität Bonn. Cerca con Google

Gallai,V.,Alberti, A., Balò, S., Mazzotta, G., Clerici, C.,Gentili, G., Firenze, C., & Morelli, A. (1995). Cognitive event-related potential in hepatic encephalopathy. Acta Neurologica Scandinavica, 91, 358–361. Cerca con Google

Garavan, H. (1998). Serial attention within working memory. Memory and Cognition, 26, 263–276. Cerca con Google

Garavan, H., Ross, T. J., & Stein, E. A. (1999). Right hemispheric dominance of inhibitory control: An event-related functional MRI study. Proceedings of the National Academy of Sciences, U.S.A., 96, 8301–8306. Cerca con Google

Gazzaley, A., Cooney, J. W., Rissman, J., & D’Esposito, M. (2005). Top-down suppression deficit underlies working memory impairment in normal aging. Nature Neuroscience, 8(10), 1298–1300. Cerca con Google

Geisser, S., & Greenhouse, S. (1959) On methods in the analysis of profile data. Psychometrika, 24, 95–112. Cerca con Google

Gilberstadt, S.J., Gilberstadt, H., Zieve, L., Buegel, B., Collier, R.O., Jr., & McClain, C.J. (1980). Psychomotor performance defects in cirrhotic patients without overt encephalopathy. Archives of Internal Medicine, 140, 519–521. Cerca con Google

Gilbert, S.J., Gollwitzer, P.M., Cohen, A.L., Burgess, P.W., & Oettingen, G. (2009). Separable brain systems supporting cued versus self-initiated realization of delayed intentions. Journal of Experimental Psychology: Learning, Memory, and Cognition, 35, 905–915. Cerca con Google

Gleckman, R.A. (1992). Urinary tract infection. Clinic in Geriatric Medicine, 8, 793–803. Cerca con Google

Grady, C. L., Bernstein, L. J., Beig, S., & Siegenthaler, A. L. (2002). The effects of encoding task on age-related differences in the functional neuroanatomy of face memory. Psychology and Aging, 17(1), 7–23. Cerca con Google

Grady, C. L., Haxby, J. V., Horwitz, B., Schapiro, M. B., Rapoport, S., Ungerleider, L. G., & Herscovitch, P. (1992). Dissociation of object and spatial vision in human extrastriate cortex: Age- related changes in activation of regional cerebral blood flow measured with [15O] water and positron emission tomography. Journal of Cognitive Neuroscience, 4, 23–34. Cerca con Google

Grady, C. L., Maisog, J. M., Horwitz, B., Ungerleider, L. G., Mentis, M. J., Salerno, J. A., et al. (1994). Age-related changes in cortical blood flow activation during visual processing of faces and location. Journal of Neuroscience, 14(3, Pt 2), 1450–1462. Cerca con Google

Grady, C. L., McIntosh, A. R., Bookstein, F., Horwitz, B., Rapoport, S. I., & Haxby, J. V. (1998). Age-related changes in regional cerebral blood flow during working memory for faces. Neuroimage, 8(4), 409–425. Cerca con Google

Grady, C. L., McIntosh, A. R., Horwitz, B., Maisog, J. M., Ungerleider, L. G., Mentis, M. J., et al. (1995). Age-related reductions in human recognition memory due to impaired encoding. Science, 269 (5221), 218–221. Cerca con Google

Gratton, G., Coles, M. G. H., Sirevaag, E. J., Eriksen, C. W., & Donchin, E. (1988). Pre- and poststimulus activation of response channels: A psychophysiological analysis. Journal of Experimental Psychology: Human Perception and Performance, 14, 331-344. Cerca con Google

Gratton, G., Coles, M.G.H., Sirevaag, E.J., Eriksen, C.W., & Donchin, E. (1988). Pre- and post-stimulus activation of response channels: A psychophysiological analysis. Journal of Experimental Psychology: Human Perception and Performance,14, 331–344. Cerca con Google

Groeneweg, M., Quero, J.C., De Bruijn, I., Hartmann, I.J., Essink-bot,M.L., Hop,W.C., & Schalm, S.W. (1998). Subclinical hepatic encephalopathy impairs daily functioning. Hepatology, 28, 45–49. Cerca con Google

Guerit, J.M., Amantini, A., Fischer, C., Kaplan, P. W., Mecarelli, O., & Schnitzler, A. (2009). Neurophysiological investigations of hepatic encephalopathy : ISHEN practice guidelines. Liver International, 789–796. Cerca con Google

Guerreiro, M. J. S., Murphy, D. R., & Van Gerven, P. W. M. (2010). The role of sensory modality in age-related distraction: a critical review and a renewed view. Psychological bulletin, 136(6), 975-1022. Cerca con Google

Gunning-Dixon, F. M., & Raz, N. (2000). The cognitive correlates of white matter abnormalities in normal aging: A quantitative review. Neuropsychology, 14(2), 224–232. Cerca con Google

Guynn, M.J. (2003). A two-process model of monitoring in event-based prospective memory: Activation/retrieval mode and checking. International Journal of Psychology, 38, 245–256. Cerca con Google

Guynn, M.J. (2008). Theory of monitoring in prospective memory: Instantiating a retrieval mode and periodic target checking. In: Kliegel M, McDaniel MA, Einstein GO, eds. Prospective memory: Cognitive, neuroscience, developmental, and applied perspectives. (pp 53–76). New York: Lawrence Erlbaum Associates. Cerca con Google

Guynn, M.J., McDaniel, M.A., & Einstein, G.O. (2001). Remembering to perform intentions: A different type of memory? In: Zimmer H.D., Cohen R.L., Guynn M.J., Engelkamp J., Kormi-Nouri R., and Foley M.A. (eds.) Memory for Action: A Distinct Form of Episodic Memory? (pp. 25–48). Oxford: Oxford University Press. Cerca con Google

Hallett, P. E. (1978). Primary and secondary saccades to goals defined by instructions. Vision Research, 18, 1279–1296. Cerca con Google

Hambrick, D.Z., Helder, E. A., Hasher, L., Zacks, R. T., & Swensen, E. (2005). The relationship between inhibition and working memory: A latent-variable approach. Paper presented at the annual meeting of the Psychonomic Society, Toronto, Ontario, Canada. Cerca con Google

Harnishfeger, K. (1995). The development of cognitive inhibition. Theories, definitions, and research evidence. In F. N. Dempster & C. J. Brainerd (Eds.), Interference and inhibition in cognition (pp. 176–206). London: Academic Press. Cerca con Google

Harris, J. E. & Wilkins, A. J. (1982). Remembering to do things: A theoretical framework and an illustrative experiment. Human Learning, 1, 123–136. Cerca con Google

Hartman, M., Dumas, J., & Nielsen, C. (2001). Age differences in updating working memory: Evidence from the delayed-matching-to-sample test. Aging, Neuropsychology, and Cognition, 8, 14–35. Cerca con Google

Hasher, L., & Zacks, R. T. (1988). Working memory, comprehension, and aging: A review and a new view. In G. H. Bower (Ed.), The Psychology of Learning and Motivation (Vol. 22, pp. 193–225). New York: Academic Press. Cerca con Google

Hasher, L., & Zacks, R.T. (1979). Automatic and effortful processes in memory. Journal of Experimental Psychology: General, 108, 356–388. Cerca con Google

Hasher, L., Zacks, R. T., & May, C. P. (1999). Inhibitory control, circadian arousal, and age. In D. Gopher & A. Koriat (Eds.), Attention and performance XVII, Cognitive regulation of performance. Interaction of theory and application (pp. 653–675). Cambridge, MA: The MIT Press. Cerca con Google

Heaton, R. K., Chelune, G. J., Talley, J. L., Kay, G.G, & Curtis, G. (1993). Wisconsin Card Sorting Test manual: Revised and expanded. Odessa, FL: Psychological Assessment Resources. Cerca con Google

Hedden, T., & Gabrieli, J. D. E. (2004). Insights into the ageing mind: a view from cognitive neuroscience. Nature reviews. Neuroscience, 5(2), 87-96. Cerca con Google

Hedden, T., & Park, D. C. (2003). Contributions of source and inhibitory mechanisms to age-related retroactive interference in verbal working memory. Journal of Experimental Psychology: General, 132, 93–112. Cerca con Google

Hedden, T., & Park, D.C. (2001). Aging and interference in verbal working memory. Psychology of Aging,16, 666. Cerca con Google

Hedden, T., & Yoon, C. (2006). Individual differences in executive processing predict susceptibility to interference in verbal working memory. Neuropsychology, 20, 511–528. Cerca con Google

Henry, J. D., MacLeod, M. S., Phillips, L. H., & Crawford, J. R. (2004). A meta-analytic review of prospective memory and aging. Psychology and Aging, 19, 27–39. Cerca con Google

Hertzog, C., Park, D., Morell, R. W., & Martin, M. (2000). Behavioural specificity in the accuracy of subjective memory complaints. Applied Cognitive Psychology, 14, 257–275. Cerca con Google

Hicks, J. L., Marsh, R. L., & Cook, G. I. (2005). Memory and Language Task interference in time-based, event-based, and dual intention prospective memory conditions. Journal of Memory and Language, 53, 430–444. Cerca con Google

Hillman, C. H., Kramer, A. F., Belopolsky, A. V., & Smith, D. P. (2006). A cross-sectional examination of age and physical activity on performance and event-related brain potentials in a task switching paradigm. International Journal of Psychophysiology, 59(1), 30–39. Cerca con Google

Hitch, G.J., & Ferguson, J. (1991). Prospective memory for future intentions: some comparisons with memory for past events, European Journal of Cognitive Psychology, 3(3), 285–295. Cerca con Google

Hölig, C., & Berti, S. (2010). To switch or not to switch: brain potential indices of attentional control after task-relevant and task-irrelevant changes of stimulus features. Brain research, 1345, 164–75. Cerca con Google

Horváth, J., Czigler, I., Birkás, E., Winkler, I., & Gervai, J. (2009). Age-related differences in distraction and reorientation in an auditory task. Neurobiology of aging, 30(7), 1157–72. Cerca con Google

Houx, P. J., Jolles, J., & Vreeling, F. W. (1993). Stroop interference: Aging effects assessed with the Stroop Color-Word Test. Experimental Aging Research, 19(3), 209–224. Cerca con Google

Hu, L., Mouraux, A., Hu, Y., & Iannetti, G.D. (2010). A novel approach for enhancing the signal-to- noise ratio and detecting automatically event-related potentials (ERPs) in single trials. Neuroimage, 50, 99–111. Cerca con Google

Hultsch, D.F., MacDonald, S.W., & Dixon, R.A. (2002). Variability in reaction time performance of younger and older adults. Journal of Gerontology Biology Psychology Science, 57, 101–115. Cerca con Google

Hultsch, D.F., MacDonald, S.W., Hunter, M.A., Levy-Bencheton, J., & Strauss, E. (2000). Intraindividual variability in cognitive performance in older adults: comparison of adults with mild dementia, adults with arthritis, and healthy adults. Neuropsychology, 14, 588–598. Cerca con Google

Huynh, H., & Feldt, L. S. (1976). Estimation of the Box correction for degrees of freedom from sample data in randomized block and split-plot designs. Journal of Educational Statistics, 1, 69–82. Cerca con Google

Insel, K., Morrow, D., Brewer, B., & Figueredo, A. (2006). Executive function,working memory, and medication adherence among older adults. Journal of Gerontology: Psychological Sciences, 61B, P102–P107. Cerca con Google

Jäger, T., & Kliegel, M. (2008). Time-based and event-based prospective memory across adulthood: Underlying mechanisms and differential costs on the ongoing task. Journal of General Psychology, 135, 4–22 Cerca con Google

Jalan R, & Bernuau J. (2007). Induction of cerebral hyperemia by ammonia plus endotoxin: does hyperammonemia unlock the blood-brain barrier? Journal of Hepatology, 47, 168–171. Cerca con Google

Jaskowski, P., & Verleger, R. (2000). An evaluation of methods for single-trial estimation of P3 latency. Psychophysiology, 37, 153–162. Cerca con Google

Jennings, J. M., & Jacoby, L. L. (1993). Automatic versus intentional uses of memory: Aging, attention, and control. Psychology and Aging, 8(2), 283–293. Cerca con Google

Joebges, E.M., Heidemann, M., Schimke, N., Hecker, H., Ennen, J.C., & Weissenborn, K. (2003). Bradykinesia in minimal hepatic encephalopathy is due to disturbances in movement initiation. Journal of Hepatology, 38, 273– 280. Cerca con Google

Johnson R, & Donchin E. (1982). Sequential expectancies and decision-making in a changing environment: an electrophysiological approach. Psychophysiology, 19, 183–200. Cerca con Google

Jonides, J., Marshuetz, C., Smith, E., Reuter-Lorenz, P. A., Keoppe, R., & Hartley, A. (2000). Age differences in behavior and PET activation reveal differences in interference resolution in verbal working memory. Journal of Cognitive Neuroscience, 12, 188–196. Cerca con Google

Joyce, C. A., Gorodnitsky, I. F., & Kutas, M. (2004). Automatic removal of eye movement and blink artifacts from EEG data using blind component separation. Psychophysiology, 41, 313–325. Cerca con Google

Jung, T. P., Makeig, S., Humphries, C., Lee, T. W., McKeown, M. J., Iragui, V., & Sejnowski, T. J. (2000). Removing electroencephalographic artifacts by blind source separation. Psychophysiology, 37, 163–178. Cerca con Google

Kaiser, S., Roth, A., Rentrop, M., Friederich, H.C., Bender, S., & Weisbrod, M. (2008). Intra- individual reaction time variability in schizophrenia, depression and borderline personality disorder. Brain and Cognition, 66, 73-82. Cerca con Google

Kane, M. J., & Engle, R. W. (2000). Working-memory capacity, proactive interference, and divided attention: Limits on long-term memory retrieval. Journal of Experimental Psychology: Learning, Memory, and Cognition, 26, 336–358. Cerca con Google

Kane, M. J., May, C. P., Hasher, L., Rahhal, T., & Stoltzfus, E. R. (1997). Dual mechanisms of negative priming. Journal of Experimental Psychology: Human Perception and Performance, 23, 632–650. Cerca con Google

Kelly, A.M., Uddin, L.Q., Biswal, B.B., Castellanos, F.X., & Milham, M.P. (2008). Competition between functional brain networks mediates behavioral variability. Neuroimage, 39, 527–537. Cerca con Google

Kennedy, K. M., & Raz, N. (2009). Aging white matter and cognition: Differential effects of regional variations in diffusion properties on memory, executive functions, and speed. Neuropsychologia, 47, 916–927. Cerca con Google

Khan, A., Sharma, N. K., & Dixit, S. (2008). Cognitive Load and Task Condition in Event- and Time-Based Prospective Memory : An Experimental Investigation. Technology, 142(5), 517–531. Cerca con Google

Kidder, D. P., Park, D. C., Hertzog, C., & Morrell, R. W. (1997). Prospective memory and aging: The effects of working memory and prospective memory task load. Aging, Neuropsychology, and Cognition, 4, 93–112. Cerca con Google

Kieffaber, P. D., & Hetrick, W. P. (2005). Event-related potential correlates of task switching and switch costs. Psychophysiology, 42(1), 56–71. Cerca con Google

Kircheis, G.,Wettstein,M., Timmermann, L., Schnitzler, A., & Haussinger, D. (2002). Critical flicker frequency for quantification of low-grade hepatic encephalopathy. Hepatology, 35, 357–366. Cerca con Google

Klein, C., Fischer, B., Hartnegg, K., Heiss, W.H., & Roth, M. (2000). Optomotor and neuropsychological performance in old age. Experimental Brain Research, 135, 141–154. Cerca con Google

Kliegel, M., Jager, T., & Phillips, L. H. (2008). Adult Age Differences in Event-Based Prospective Memory : A Meta-Analysis on the Role of Focal Versus Nonfocal Cues. Psychology and Aging, 23(1), 203–208. Cerca con Google

Kliegel, M., Jäger, T., Altgassen, M., & Shum, D. (2008). Clinical neuropsychology of prospective memory. In M. Kliegel, M. A. McDaniel, & G. O. Einstein (Eds.), Prospective memory (pp. 283–308). NewYork: Erlbaum. Cerca con Google

Kliegel, M., Martin, M., & Moor, C. (2003). Prospective memory and aging: Is task importance relevant? International Journal of Psychology, 38, 207–214. Cerca con Google

Kliegel, M., Martin, M., McDaniel, M. A., & Einstein, G. O (2002). Complex prospective memory and executive control of working memory: A process model. Psychologische Beiträge, 44, 303–318. Cerca con Google

Kliegel, M., Ramuschkat, G., & Martin, M. (2003). Exekutive Funktionen und prospektive Gedär chtnisleistung im Alter: Eine differentielle Analyse von ereignis- und zeitbasierter prospektiver prospektive Gedächtnisleistung [Executive functions and prospective memory performance in old age: An analysis of event-based and time-based prospective memory]. Zeitschrift für Gerontologie und Geriatrie, 36, 35–41. Cerca con Google

Knight, J. B., Ethridge, L. E., Marsh, R. L., & Clementz, B. A. (2010). Neural correlates of attentional and mnemonic processing in event-based prospective memory. Frontiers in human neuroscience, 4, 5. Cerca con Google

Kok, A. (1999). Varieties of inhibition: Manifestations in cognition, event- related potentials and aging. Acta Psychologica, 101, 129–158. Cerca con Google

Kok, A. (2001). On the utility of P3 amplitude as a measure of processing capacity. Psychophysiology, 38, 557–577. Cerca con Google

Kok, A., Ramautar, J.R., De Ruiter, M.B., Band, G.P., & Ridderinkhof, K.R. (2004). ERP components associated with successful and unsuccessful stopping in a stop-signal task. Psychophysiology, 41(1), 9–20. Cerca con Google

Konishi, S., Nakajima, K., Uchida, I., Kikyo, H., Kameyama, M., & Miyashita, Y. (1999). Common inhibitory mechanism in human inferior prefrontal cortex revealed by event-related functional MRI. Brain, 122, 981–991. Cerca con Google

Kono, I., Ueda, Y., Nakajima, K., Araki, K., Kagawa, K., & Kashima, K. (1994). Subcortical impairment in subclinical hepatic encephalopathy. Journal of the Neurological Sciences, 126, 162–167. Cerca con Google

Kopp, B., Mattler, U., Goertz, R., & Rist, F. (1996). N2, P3 and the lateralized readiness potential in a nogo task involving selective response priming. Electroencephalography & Clinical Neurophysiology, 99, 19–27. Cerca con Google

Kramer, A.F., Humphrey, D.G., Larish, J.F., Logan, G.D., & Strayer, D.L. (1994). Aging and inhibition: Beyond a unitary view of inhibitory processing in attention. Psychology and Aging, 9, 491–512. Cerca con Google

Kramer, L., Bauer, E., Gendo, A., Funk, G., Madl, C., Pidlich, J., & Gangl, A. (2002). Neurophysiological evidence of cognitive impairment in patients without hepatic encephalopathy after transjugular intrahepatic portosystemic shunts. American Journal of Gastroenterology, 97,162–166. Cerca con Google

Kray, J., & Lindenberger, U. (2000). Adult age differences in task switching. Psychology and Aging, 15(1), 126–147. Cerca con Google

Kulisevsky, J., Conill, J., Avila, A., Pujol, J., Balanzo, J., & Capdevila, A. (1995). Abnormalities of the Bereitschaftspotential and MRI pallidal signal in non-encephalopathic cirrhotic patients. Electroencephalography and Clinical Neurophysiology, 94, 425–431. Cerca con Google

Kullmann, F., Hollerbach, S., Holstege, A., & Scholmerich, J. (1995). Subclinical hepatic encephalopathy: The diagnostic value of evoked potentials Journal of Hepatology,22, 101–110. Cerca con Google

Kutas, M., McCarthy, G., & Donchin, E. (1977). Augmenting mental chronometry: The P300 as a measure of stimulus evaluation time. Science, 197, 792–795. Cerca con Google

Kvavilashvili, L., & Ellis, J. (1996). Varieties of intentions: Some distinctions and classifications. In M. Brandimonte, G. O. Einstein, & M. A. McDaniel (Eds.), Prospective memory: Theory and applications (pp. 23–52). Mahwah, NJ: Erlbaum. Cerca con Google

Kvavilashvili, L., & Fisher, L. (2007). Is time-based prospective remembering mediated by self-initiated rehearsals? Role of cues, ongoing activity, age and motivation. Journal of Experimental Psychology: General, 136, 112–132. Cerca con Google

Lamar, M., Yousem, D. M., & Resnick, S. M. (2004). Age differences in orbitofrontal activation: An fMRI investigation of delayed match and non-match to sample. Neuroimage, 21(4), 1368–1376. Cerca con Google

Lawrence, M.A. (2011) ez: Easy analysis and visualization of factorial experiments. R package version 3.0-0. http://CRAN.R-project.org/package=ez Vai! Cerca con Google

Li, S.C., & Lindenberger, U. (1999). Cross-level unification: a computational exploration of the link between deterioration of neurotransmitter systems and dedifferentiation of cognitive abilities in old age. In: Nilsson LG, Markowitsch H. Cognitive neuroscience of memory. (pp. 103–146). Berlin (Germany): Hogrefe and Huber. Cerca con Google

Lindenberger, U., & Baltes, P. B. (1994). Sensory functioning and intelligence in old age: A strong connection. Psychology and Aging, 9(3), 339–355. Cerca con Google

Liotti, M., Woldorff, M. G., Perez, R., & Mayberg, H. S. (2000). An ERP study of the temporal course of the Stroop color-word interference effect. Neuropsychologia, 38, 701–711. Cerca con Google

Liu, L. L., & Park, D. C. (2004). Aging and medical adherence: The use of automatic processes to achieve effortful things. Psychology and Aging, 19, 318–325. Cerca con Google

Lizardi-cervera, J., Almeda, P., Guevara, L., & Uribe, M. (2003). Hepatic encephalopathy : A review. Gastroenterology, 2(3). Cerca con Google

Lobaugh, N. J., West, R., & McIntosh, A. R. (2001). Spatiotemporal analysis of experimental differences in event-related potential data with partial least squares. Psychophysiology, 38(3), 517–530. Cerca con Google

Lockwood, A.H., Murphy, B.W., Donnelly, K.Z., Mahl, T.C., & Perini, S. (1993). Positron-emission tomographic localization of abnormalities of brain metabolism in patients with minimal hepatic encephalopathy. Hepatology, 18, 1061–1068. Cerca con Google

Lockwood, A.H., Yap, E.W.H., Rhoades, H.M., & Wong, W.-H. (1991). Altered cerebral blood flow and glucose metabolism in patients with liver disease and minimal encephalopathy. Journal of Cerebral Blood Flow and Metabolism, 11, 331–336. Cerca con Google

Logan, G. D., & Bundesen, C. (2003). Clever homunculus: Is there an endogenous act of control in the explicit task cuing procedure? Journal of Experimental Psychology: Human Perception & Performance, 29, 575–599. Cerca con Google

Logan, G.D. (1994). On the Ability to Inhibit Thought and Action: A User’s guide to the Stop Signal Paradigm. In: Dagenbach, D., Carr, T.H. (Eds.), Inhibitory Processes in Attention, Memory, and Language. (pp. 189–239). Academic Press, San Diego. Cerca con Google

Logan, J. M., Sanders, A. L., Snyder, A. Z., Morris, J. C., & Buckner, R. L. (2002). Under-recruitment and nonselective recruitment: Dissociable neural mechanisms associated with aging. Neuron, 33, 827–840. Cerca con Google

Logie, R. H., Maylor, E. A., Della Sala, S., & Smith, G. (2004). Working memory in event- and time-based prospective memory tasks: Effects of secondary demand and age. The European Journal of Cognitive Psychology, 16, 444– 456. Cerca con Google

Luck, S. J., & Hillyard, S. A. (1994). Electrophysiological correlates of feature analysis during visual search. Psychophysiology, 31, 291–308. Cerca con Google

Lustig, C., Hasher, L., & Tonev, S. T. (2006). Distraction as a determinant of processing speed. Psychonomic Bulletin & Review, 13, 619–625. Cerca con Google

Lustig, C., May, C. P., & Hasher, L. (2001). Working memory span and the role of proactive interference. Journal of Experimental Psychology: General, 130, 199–207. Cerca con Google

Luszcz, M. A., & Lane, A. P. (2008). Executive function in cognitive neuropsychological, and clinical aging. In S. M. Hofer, & D. F. Alwin (Eds.), Handbook of cognitive aging: Interdisciplinary perspectives. London: Sage Publications. Cerca con Google

MacDonald, S.W., Nyberg, & L., Backman, L. (2006). Intra-individual variability in behavior: links to brain structure, neurotransmission and neuronal activity. Trends in Neuroscience, 29, 474–480. Cerca con Google

Mack, A., & Rock, I. (1998). Inattentional Blindness. Cambridge, MA: MIT Press, 1998. Cerca con Google

Magliero, A., Bashore, T.R., Coles, M.G., & Donchin, E. (1984). On the dependence of P300 latency on stimulus evaluation processes. Psychophysiology, 21, 171–186. Cerca con Google

Mäntylä, T., & Carelli, M. G. (2006). Time monitoring and executive functioning: Individual and developmental differences. In J. Glickson & M. Myslobodsky (Eds.), Timing the future: The case for a time-based prospective memory (pp. 191–211). New York: World Scientific. Cerca con Google

Mäntylä, T., & Nilsson, L.G. (1997). Remembering to remember in adulthood: A population-based study of aging and prospective memory. Aging, Neuropsychology, & Cognition, 4, 81–92. Cerca con Google

Mäntylä, T., Carelli, M. G., & Forman, H. (2007). Time monitoring and executive functioning in children and adults. Journal of Experimental Child Psychology, 96, 1–19. Cerca con Google

Mäntylä, T., Missier, F. D., & Nilsson, L.G. (2009). Age differences in multiple outcome measures of time-based prospective memory. Neuropsychology, development, and cognition. Section B, Aging, neuropsychology and cognition, 16(6), 708–720. Cerca con Google

Marsh, R. L., Hicks, J. L., & Cook, G. I. (2005). On the relationship between effort toward an ongoing task and cue detection in event-based prospective memory. Journal of Experimental Psychology: Learning, Memory, and Cognition, 31, 68–75. Cerca con Google

Marsh, R. L., Hicks, J. L., & Cook, G. I. (2006). Task interference from prospective memories covaries with contextual associations of fulfilling them. Memory & Cognition, 34, 1037–1045. Cerca con Google

Marsh, R. L., Hicks, J. L., & Hancock, T. W. (2000). On the interaction of ongoing cognitive activity and the nature of an event-based intention. Applied Cognitive Psychology, 14, S29–S41. Cerca con Google

Marsh, R. L., Hicks, J. L., & Watson, V. (2002). The dynamics of intention retrieval and coordination of action in event-based prospective memory. Journal of Experimental Psychology: Learning, Memory, and Cognition, 28, 652–660. Cerca con Google

Marsh, R. L., Hicks, J. L., Cook, G. I., Hansen, J. S., & Pallos, A. L. (2003). Interference to ongoing activities covaries with the characteristics of an event-based intention. Journal of Experimental Psychology: Learning, Memory, and Cognition, 298, 861–870. Cerca con Google

Marsh, R.L., & Hicks, J.L. (1998). Event-based prospective memory and executive control of working memory. Journal of Experimental Psychology: Learning, Memory, and Cognition, 24, 336–349. Cerca con Google

Martin, M. (1986). Ageing and patterns of change in everyday memory and cognition. Human Learning, 5, 63-74. Cerca con Google

Martin, M., & Schumann-Hengsteler, R. (2001). How task demands influence time-based prospective memory performance in young and older adults. International Journal of Behavioral Development, 25, 386–391. Cerca con Google

Martin, M., Kliegel, M., & McDaniel, M. A. (2003). The involvement of executive functions in prospective memory performance of adults. International Journal of Psychology, 38, 195–206. Cerca con Google

Masini A, Efrati C, Merli M, Nicolao F, Amodio P, Del Piccolo F, & Riggio, O. (2003). Effect of blood ammonia elevation following oral glutamine load on the psychometric performance of cirrhotic patients. Metabolic Brain Disease, 18, 27–35. Cerca con Google

Mattli, F., Zöllig, J., & West, R. (2011). Age-related differences in the temporal dynamics of prospective memory retrieval: A lifespan approach. Neuropsychologia, 49(12), 3494–504. Cerca con Google

May, C. P., Zacks, R. T., Hasher, L., & Multhaup, K. S. (1999). Inhibition in the processing of garden-path sentences. Psychology and Aging, 14, 304–313. Cerca con Google

Maylor E A, Smith G, Della Sala S, & Logie R H. (2002). Prospective and retrospective memory in normal aging and dementia: An experimental study. Memory and Cognition, 20, 871–884. Cerca con Google

Maylor, E. A. (1993). Aging and forgetting in prospective and retro- spective memory tasks. Psychology & Aging, 3, 420–428. Cerca con Google

Maylor, E. A. (1995). Prospective memory in normal ageing and dementia. Neurocase, 1, 285–289. Cerca con Google

Maylor, E. A. (1996). Age-related impairment in an event-based prospective memory task. Psychology and Aging, 11, 74–79. Cerca con Google

Maylor, E. A. (1998). Changes in event-based prospective memory across the adulthood. Aging, Neuropsychology, and Cognition, 5, 107–128. Cerca con Google

Maylor, E. A., & Lavie, N. (1998). The influence of perceptual load on age differences in selective attention. Psychology and Aging, 13, 563–573. Cerca con Google

Mayr, U. (2001). Age differences in the selection of mental sets: The role of inhibition, stimulus ambiguity, and response-set overlap. Psychology and Aging, 16(1), 96–109. Cerca con Google

Mayr, U., & Keele, S. (2000). Changing internal constraints on action: The role of backward inhibition. Journal of Experimental Psychology: General, 129, 4–26. Cerca con Google

McCrea, M., Cordoba, J., Vessey, G., Blei, A.T., & Randolph, C. (1996). Neuropsychological characterization and detection of subclinical hepatic encephalopathy. Archives of Neurology. 53, 758–763. Cerca con Google

McDaniel M, Einstein G, & Rendell P. (2008) The puzzle of inconsistent age- related declines in prospective memory: A multiprocess explanation. In K. Matthias, ed. Prospective memory (pp 141–160). Cerca con Google

McDaniel, M. A, & Einstein, G. O. (2011). The neuropsychology of prospective memory in normal aging: A componential approach. Neuropsychologia. 49(8), 2147–2155. Cerca con Google

McDaniel, M. A., & Einstein, G. O. (2000). Strategic and automatic processes in prospective memory retrieval: A multiprocess framework. Applied Cognitive Psychology, 14, S127–S144. Cerca con Google

McDaniel, M. A., Einstein, G. O., Stout, A. C., & Morgan, Z. (2003). Aging and maintaining intentions over delays: Do it or lose it. Psychology and Aging, 18, 823–835. Cerca con Google

McDaniel, M. A., Glisky, E. L., Rubin, S. R., Guynn, M. J., & Routhieaux, B. C. (1999). Prospective memory: A neuropsychological study. Neuropsychology, 13, 103–110. Cerca con Google

McDaniel, M. A., Guynn, M. J., Einstein, G. O., & Breneiser, J. (2004). Cue-focused and automatic-associative processes in prospective memory retrieval. Journal of Experimental Psychology: Learning, Memory, and Cognition, 30, 605–614. Cerca con Google

McDaniel, M. A., Robinson-Riegler, B., & Einstein, G. O. (1998). Prospective remembering: Perceptually driven or conceptually driven processes? Memory & Cognition, 26, 121–134. Cerca con Google

McFarland, C. P., & Glisky, E. L. (2009). Frontal lobe involvement in a task of time-based prospective memory. Neuropsychologia, 47(7), 1660–1669. Cerca con Google

McIntosh, A. R., Bookstein, F. L., Haxby, J.V., & Grady, C. L. (1996). Spatial pattern analysis of functional brain images using partial least squares. NeuroImage, 3, 143–157. Cerca con Google

Mehndiratta, M.M., Sood, G.K., Sarin, S.K., & Gupta, M. (1990). Comparative evaluation of visual, somatosensory, and auditory evoked potentials in the detection of subclinical hepatic encephalopathy in patients wi Cerca con Google

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