Modulation of a fronto-parietal network in event-based prospective memory: an rTMS study

Event-based prospective memory (PM) is a multi-component process that requires remembering the delayed execution of an intended action in response to a pre-specified PM cue, while being actively engaged in an ongoing task. Some neuroimaging studies have suggested that both prefrontal and parietal areas are involved in the maintenance and realization of delayed intentions. In the present study, transcranial magnetic stimulation (TMS) was used to investigate the causal involvement of frontal and parietal areas in different stages of the PM process (in particular, target checking and intention retrieval), and to determine the specific contribution of these regions to PM performance.Our results demonstrate that repetitive TMS (rTMS) interferes with prospective memory performance when applied at 150-350 ms to the right dorsolateral prefrontal cortex (DLPFC), and at 400-600 ms when applied to the left posterior parietal cortex (PPC).The present study provides clear evidence that the right DLPFC plays a crucial role in early components of the PM process (target checking), while the left PPC seems to be mainly involved in later processes, such as the retrieval of the intended action.     

Dissociative contributions of medial temporal and frontal regions to prospective remembering

Prospective memory is memory of future intentions or plans in everyday life. Although some previous neuropsychological studies have stated that the prefrontal cortex and the medial temporal lobe are essential for successful prospective remembering, how the two regions contribute to prospective remembering remains unclear. We therefore used prospective memory training in the present study to investigate the neural mechanism of two components of prospective remembering: remembering to remember and remembering content. Two brain-damaged patients participated in this study: patient Y.O., who had lesions in the medial temporal lobe bilaterally, and patient T.K., who had a lesion in the basal forebrain and right medial frontal lobe. Both participants exhibited a severe anterograde amnesic syndrome and had normal IQ scores. Before the prospective memory training the participants underwent several index memory tests to examine their general memory and prospective memory performance. The training consisted of requesting the participants to perform an original mini-day task, in which they were first asked to memorize five simple daily actions with their times for execution, and then to recall the content of the actions when shown a drawing of a clock showing the proper time for execution. A training session was carried out once a week for 3 months. After completing training, the participants were again requested to take the same index memory tests. The results of the training task showed that Y.O.'s memory performance had gradually improved across all sessions of training, but T.K.'s improvement was not as marked. A more detailed analysis revealed that Y.O.'s memory performance was better for recalling time than for recalling content, whereas T.K.'s memory performance was better for recalling content than for recalling time. Furthermore, the results of the final index memory tests showed that the only improvement in Y.O.'s prospective memory was in remembering to remember, and that the only improvement in T.K.'s prospective memory was in remembering content. These results provide strong evidence that these two remembering components of prospective memory have independent neural bases, with the basal forebrain and right medial frontal lobe being required for remembering to remember, and the medial temporal lobe being required for remembering content. The results also suggest that memory training is an effective, means of improving everyday memory.     

Characteristics of prospective memory deficits in HIV-seropositive substance-dependent individuals: preliminary observations

The construct of "prospective memory" (PM) refers to a type of episodic memory for a future intention or "remembering what one must do." This function has been proposed as a candidate mechanism underlying behaviors of critical importance in HIV disease, including adherence with medication regimens and continued engagement in risk behavior. We administered tasks of time-based and event-based prospective memory and control tasks of retrospective and working memory to 31 HIV-seropositive and 35 HIV-seronegative substance-dependent individuals (SDIs). We found that compared with HIV- controls HIV+ participants showed deficits in time-based but not event-based PM. Retrospective, but not working, memory performance correlated significantly with time-based PM performance. In addition, performance on the time-based PM task was a significant predictor of scores on a self-report measure of risky sexual and injection practices. These preliminary data provide new and unique findings regarding the components of executive function mediated by prefrontal cortical systems that are impaired among HIV+ SDIs and their relevance to "real-world" behaviors.     

The role of rostral prefrontal cortex in prospective memory: a voxel-based lesion study

Patients with lesions in rostral prefrontal cortex (PFC) often experience problems in everyday-life situations requiring multitasking. A key cognitive component that is critical in multitasking situations is prospective memory, defined as the ability to carry out an intended action after a delay period filled with unrelated activity. The few functional imaging studies investigating prospective memory have shown consistent activation in both medial and lateral rostral PFC but also in more posterior prefrontal regions and non-frontal regions. The aim of this study was to determine regions that are necessary for prospective memory performance, using the human lesion approach. We designed an experimental paradigm allowing us to assess time-based (remembering to do something at a particular time) and event-based (remembering to do something in a particular situation) prospective memory, using two types of material, words and pictures. Time estimation tasks and tasks controlling for basic attention, inhibition and multiple instructions processing were also administered. We examined brain-behaviour relationships with a voxelwise lesion method in 45 patients with focal brain lesions and 107 control subjects using this paradigm. The results showed that lesions in the right polar prefrontal region (in Brodmann area 10) were specifically associated with a deficit in time-based prospective memory tasks for both words and pictures. This deficit could not be explained by impairments in basic attention, detection, inhibition or multiple instruction processing, and there was also no deficit in event-based prospective memory conditions. In addition to their prospective memory difficulties, these polar prefrontal patients were significantly impaired in time estimation ability compared to other patients. The same region was found to be involved using both words and pictures, suggesting that right rostral PFC plays a material nonspecific role in prospective memory. This is the first lesion study showing that rostral PFC is crucial for time-based prospective memory. The findings suggest that time-based and event-based prospective memory might be supported at least in part by distinct brain regions. Two particularly plausible explanations for the deficit rest upon a possible role for polar prefrontal structures in supporting in time estimation, and/or in retrieving an intention to act. More broadly, the results are consistent with the view that the deficit of rostral patients in multitasking situations might at least in part be explained by a deficit in prospective memory.     

Prospective memory and mesial temporal epilepsy associated with hippocampal sclerosis

Episodic memory impairment is commonly observed in patients with epilepsy associated with mesial temporal sclerosis (MTS). Prospective memory (PM) is a set cognitive abilities that allow future performance of a present intention, in response to time- or event-based evocation cues, that trigger the intended action at the appropriate time. PM has not been evaluated in mesial temporal sclerosis. We evaluated the role of right and left hippocampal lesions on performance in both the retrospective and prospective PM components in patients with epilepsy secondary to mesial temporal sclerosis and correlated with performance in traditional neuropsychological tests, as well as with self-perception of memory impairment. We tested the hypotheses that a hippocampal lesion impacts on the prospective components of PM, and that a left-sided lesion had a greater impact on performance in the prospective component of PM than a right-sided lesion. We evaluated PM in 26 patients with right MTS, 22 left MTS patients, and 26 age-gender and education matched controls. The prospective component of PM was impaired in both patient groups, with both a lesion (patients performed significantly worse in the PM battery) and laterality effect (left MTS patients performed significantly worse than right MTS patients in the PM battery). Performance in the prospective component of the PM battery correlated with long-term delay performance in episodic verbal memory and self-perception of memory impairment in the left MTS group. The retrospective component was impaired in left MTS patients. Impaired performance was not accounted for solely by depression, anxiety or an antiepileptic drug effect. We conclude that mesial temporal lobe structures, including the hippocampus, play an important role in both the prospective and retrospective components of PM processes in tasks involving long delay intervals.     

A role for right medial prefontal cortex in accurate feeling-of-knowing judgements: evidence from patients with lesions to frontal cortex

The hypothesis that prefrontal cortex plays a critical role in accurate predictions of episodic memory performance was tested using the feeling-of-knowing (FOK) paradigm. Fourteen patients with a broad spectrum of damage to the frontal cortex and matched controls read sentences and later were tested for recall memory, confidence judgments, and FOK accuracy using as cues the sentences with the final word missing. While frontal patients were impaired at recall and recognition memory, they were able to make accurate confidence judgments about their recall attempts. By contrast, as a group, the patients were markedly impaired in the accuracy of their prospective FOK judgments. Lesion analysis of frontal patients with clear FOK impairment revealed an overlapping region of damage in right medial prefrontal cortex. These findings provide functional and anatomical evidence for a dissociation between recall confidence and prospective memory monitoring and are discussed in terms of familiarity and access theories of FOK predictions.     

Face memory impairments in patients with frontal lobe damage

OBJECTIVE: To determine whether damage to prefrontal cortex is associated with face memory impairment. BACKGROUND: Neurophysiologic and functional imaging studies suggest that prefrontal cortex is a key component of a distributed neural network that mediates face recognition memory. However, there have been few attempts to examine the impact of frontal lobe damage on face memory performance. METHODS:Patients with focal frontal lobe lesions and normal control subjects were administered two-alternative forced-choice and single-probe "yes/no" tests of recognition memory for novel faces. Retrograde memory was assessed by using famous faces as stimuli. RESULTS: Compared with control subjects, patients with frontal lobe lesions showed evidence of marked anterograde and relatively mild retrograde face memory impairment. In addition, patients with right frontal lesions demonstrated increased susceptibility to false recognition, consistent with the breakdown of strategic memory retrieval, monitoring, and decision functions. CONCLUSIONS: Prefrontal cortex plays an important role in the executive control of face memory encoding and retrieval. Left and right prefrontal regions seem to make different contributions to recognition memory performance.     

Looking to the future: automatic regulation of attention between current performance and future plans

We investigated neuro-cognitive mechanisms involved with coordination of attention between current task performance and future action plans in prospective memory. We developed a novel task paradigm with continuous performance of a prospective memory task, where trial intervals of prospective memory targets were systematically manipulated in a periodic cycle of expanding and contracting target intervals. We found that subjects’ behaviour was significantly modulated without awareness of this temporal sequence of the targets: remembering to perform a prospective memory response to target events was more successful and faster in the expanding target interval phase, at the cost of lower and slower performance of ongoing tasks, while an opposite direction of this trade-off effect was observed in the contracting target interval phase. By using functional magnetic resonance imaging (fMRI), we identified the similar trade-off effect in activations in the anterior medial prefrontal cortices (activation elevation at the target responses as well as deactivation at the ongoing responses in the expanding phase as compared with the contracting phase). The opposite direction of the trade-off was observed in the anterior cingulate cortex. These results show a clear case in which attention between current task performance and future action plans in prospective memory tasks is automatically regulated without particular task instructions or strategic control processes initiated by subjects. We suggest that medial areas of the frontal cortex specifically mediate the automatic coordination of attentional resources between current task performance and future action plans.     

Performance of schizophrenia patients on time-, event-, and activity-based prospective memory tasks

The present study aimed to determine whether individuals with long-term schizophrenia have impaired prospective memory (PM), the ability to remember to perform intended actions in the future. Three PM tasks (time-, event-, and activity-based) were administered to 60 schizophrenia patients and 60 matched controls. Patients performed significantly more poorly than controls on all three tasks. The between-group difference was disproportionately larger on the time-based task, a task that required a prefrontal lobe process called self-initiated retrieval. To examine the relationship between PM and prefrontal lobe functions, subjects were also administered the Design Fluency Test (DFT), the Tower of London (TOL), and the Wisconsin Card Sorting Test (WCST). For patients, performance on the event-based task was found to correlate significantly with performance on the DFT, and performance on the time-based task was found to correlate significantly with performance on the TOL. Results of this study support the importance and contribution of prefrontal lobe processes in prospective remembering and have implications for the assessment and treatment of individuals with schizophrenia.     

Can we remember future actions yet forget the last two minutes? Study in transient global amnesia

Transient global amnesia (TGA) is a clinical syndrome characterized by the abrupt onset of a massive episodic memory deficit that spares other cognitive functions. If the anterograde dimension is known to be impaired in TGA, researchers have yet to investigate prospective memory (PM)--which involves remembering to perform an intended action at some point in the future--in this syndrome. Furthermore, as executive functions are thought to be spared in this syndrome, TGA provides an opportunity to examine the impact of a massive "pure" memory impairment on PM. We assessed 38 patients with a newly designed protocol that distinguished between the prospective (remembering to do something at the appropriate time) and retrospective (remembering what has to be done) components of PM. Moreover, we investigated episodic memory with an anterograde memory task and assessed executive functions, anxiety and mood, as well as their links with PM. We demonstrated that PM is impaired during TGA, with a greater deficit for the retrospective component than for the prospective component. Furthermore, we highlighted a strong link between these two components. Anterograde episodic memory impairments were correlated with retrospective component deficits in TGA patients, although we were able to confirm that executive functions are globally spared. We discuss this pattern of results within the theoretical framework of PM, putting forward new arguments in favor of the idea that PM deficits can occur mainly because of a massive anterograde memory deficit. The clinical consequences of PM impairment in TGA are examined.     

Cognitive performance and neural correlates of detecting driving hazards in healthy older adults

BACKGROUND/AIMS: In spite of the growing number of seniors who drive and their relatively frequent involvement in accidents, little is known about the cognitive substrates of road hazard recognition and their relationship with general cognitive performance in this population. We aimed to investigate, using a combination of functional MRI (fMRI) and a comprehensive neuropsychological battery, the anatomical and cognitive components of driving hazard recognition. METHODS: Fourteen healthy active drivers aged between 65 and 87 years underwent neuropsychological evaluation and fMRI scanning. fMRI was performed while subjects watched a video composed of clips of driving hazards randomly interspersed with uneventful driving clips. We investigated brain areas that are recruited for hazard detection, in contrast to brain areas responding to driving without a hazard. The performance on neuropsychological tests was then regressed with the degree of activation of cortical areas related exclusively to detecting hazards. RESULTS: Driving hazards generated significant activations, compared to non-hazards, in the lateral associative occipital cortex and in the right prefrontal cortex. Intensity of brain activation was correlated on performance on memory and cognitive control neuropsychological tests. CONCLUSION: Future studies can possibly address the same relationship in early dementia, as a preliminary form of investigation for driving safety.     

The cognitive and neuroanatomical correlates of multitasking

Patients who show the "strategy application disorder" can show deficits restricted to situations requiring multitasking, but the precise neuroanatomical and cognitive correlates of this problem have been rarely investigated. In this study, 60 people with circumscribed cerebral lesions and 60 age- and IQ-matched controls were given a multitasking procedure which allowed consideration of the relative contributions of task learning and remembering, planning, plan-following and remembering one's actions to multitasking performance. Lesions to the left posterior cingulate and forceps major regions gave deficits on all measures except planning. Remembering task contingencies after a delay was also affected by lesions in the region of the left anterior cingulate, and rule-breaking and failures of task switching were additionally found in people with lesions affecting the medial and more polar aspects of Brodmann's areas 8, 9 and especially 10. Planning deficits were associated with lesions to the right dorsolateral prefrontal cortex (RDLPFC). A theory of the relationships between the cognitive constructs underpinning multitasking was tested using structural equation modelling. The results suggest that there are three primary constructs that support multitasking: retrospective memory, prospective memory, and planning, with the second two drawing upon the products of the first. It is tentatively suggested that the left anterior and posterior cingulates together play some part in the retrospective memory demands, while the prospective memory and planning components make demands on processes supported by the left areas 8, 9 and 10 and the RDLPFC respectively.     

Working memory dysfunction in obsessive-compulsive disorder: A neuropsychological and functional MRI study

Previous neuropsychological studies indicate that OCD subtypes such as checking rituals might be associated with a working memory deficit. On the other hand, functional neuroimaging studies found functional abnormalities of the frontal cortex and subcortical structures in OCD. Combined with functional imaging method, we applied neuropsychological batteries to demonstrate a working memory deficit in OCD by comparison with normal controls. In addition, working memory and brain activation were further examined with symptom-based analysis. Forty patients with OCD and 25 normal controls were examined using neuropsychological tests including the WAIS-R, WCST, WMS-R, and R-OCFT and functional MRI (fMRI) during the N-back task including 0- and 2-back task. On fMRI, the brain regions activated during the performance and the differences in the activation between patients and controls were identified. Additional analyses of severity and subtypes were conducted by using Y-BOCS severity score, symptom-checklist and Leckman’s four-factor model, respectively. On the neuropsychological tests, the OCD patients had significantly lower scores on the delayed recall section of the WMS-R and the immediate recall section of the R-OCFT compared to the controls. On fMRI, the patients showed greater activation in the right dorsolateral prefrontal cortex (DLPFC), left superior temporal gyrus (STG), left insula, and cuneus during two-back task compared to the controls. Right orbitofrontal cortex activity showed a significant positive correlation with Y-BOCS scores in OCD. Furthermore, patients with obsessions/checking rituals (n = 10) showed severer memory deficits and decreased activity in the postcentral gyrus than patients with cleanliness/washing rituals (n = 14). In conclusion, we found neuropsychological dysfunction and brain abnormalities in OCD. Furthermore, our results suggested that symptom severity and symptom subtype such as obsessions/checking might affect neuropsychological dysfunction and related brain activities.     

Prospective memory and working memory: Asymmetrical effects during frontal lobe TMS stimulation

The role of working memory (WM) for the realization of an intended action (prospective memory, PM) has been debated in recent neuropsychological literature. The present study aimed to assess whether WM and PM share resources or are, alternatively, two distinct mechanisms. A verbal task was used, which manipulated the cognitive demand of both WM and PM dimensions on an event-based prospective task. Transcranial magnetic stimulation (TMS) was also employed to clarify the causal contribution of frontal areas previously related to WM, to the PM process. The prospective task required the participant to respond whenever a word appeared which had been presented before the beginning of the task. Two ongoing tasks were administered: an updating WM task (in two conditions of medium and high WM demands) and a lexical decision task (representing a low WM demand). In the first two experiments, higher PM demand affected WM only at higher loads, but the PM load effect was independent of WM, showing asymmetrical behavioural effects. In the third experiment, single pulse TMS was applied to left and right dorsolateral prefrontal cortices. When applied to the experimental sites, stimulation increased error rates of the PM task, while the effect was only marginal in the WM task. The effect was bilateral, since there was no difference between left and right stimulation sites. These findings demonstrated, from both behavioural and neurofunctional perspectives, that WM and PM processes are not based on the same memory system, but PM may require WM resources at high demand.     

Working memory and prefrontal cortex dysfunction: specificity to schizophrenia compared with major depression.

BACKGROUND: A large number of studies suggest the presence of deficits in dorsolateral prefrontal cortex function during performance of working memory tasks in individuals with schizophrenia. However, working memory deficits may also present in other psychiatric disorders, such as major depression. It is not clear whether people with major depression also demonstrate impaired prefrontal activation during performance of working memory tasks. METHODS: We used functional magnetic resonance imaging to assess the patterns of cortical activation associated with the performance of a 2-back version of the N-Back task (working memory) in 38 individuals with schizophrenia and 14 with major depression. RESULTS: We found significant group differences in the activation of dorsolateral prefrontal cortex associated with working memory performance. Consistent with prior research, participants with schizophrenia failed to show activation of right dorsolateral prefrontal cortex in response to working memory tasks demands, whereas those with major depression showed clear activation of right and left dorsolateral prefrontal cortex as well as bilateral activation of inferior and superior frontal cortex. CONCLUSIONS: During performance of working memory tasks, deficits in prefrontal activation, including dorsolateral regions, are more severe in participants with schizophrenia (most of whom were recently released outpatients) than in unmedicated outpatients with acute nonpsychotic major depression.     

A neuropsychological investigation of prefrontal cortex involvement in acute mania

OBJECTIVE: Mania has received little attention from a contemporary neuropsychological perspective despite its clear resemblance to the disinhibition syndrome sometimes seen after frontal brain injury, particularly injury to the inferior aspect of the prefrontal cortex. The purpose of this investigation was to describe the neuropsychological profile of severe acute mania by using a range of tasks selected primarily for the detection of localized neural disruption within the prefrontal cortex. METHOD: Fifteen acutely manic inpatients were compared with 30 nonpsychiatric subjects on tasks from the Cambridge Automated Neuropsychological Test Battery (Tower of London, spatial working memory, intradimensional-extradimensional attentional shift, and rapid visual information processing tasks) and on the Iowa Gambling Task, Stroop Color and Word Test, a verbal fluency task, and the California Verbal Learning Test. RESULTS: Discriminant function analysis identified deficits in sustained attention (on the rapid visual information processing task) and verbal learning (on the California Verbal Learning Test) as the best indicators of manic performance, rather than deficits on any of the tests of executive functioning. The model correctly classified 91% of subjects overall and 87% of manic subjects. Manic patients did not resemble patients with ventromedial prefrontal cortex damage in their performance on the Iowa Gambling Task. CONCLUSIONS: Acute mania is characterized by core deficits in verbal memory and sustained attention against a background of milder impairments in functions that are traditional measures of prefrontal cortex integrity (attentional set shifting, planning, working memory). The data do not implicate ventral prefrontal cortex disruption as a locus of pathology in acute mania. Verbal memory and sustained attention deficits may relate differentially to the state and trait characteristics of bipolar disorder.     

Transcranial brain stimulation studies of episodic memory in young adults, elderly adults and individuals with memory dysfunction: a review

Transcranial magnetic and electric stimulation studies examining episodic memory in young participants have established the role of the left prefrontal cortex during encoding and the right prefrontal cortex during episodic retrieval. Furthermore, these techniques have been used to verify the reduction in functional asymmetry in the prefrontal cortex that occurs with ageing, at least during encoding, suggesting the existence of compensatory adjustments for the structural and neurotransmitter loss that occurs with physiological ageing. Nevertheless, it has been shown that several factors can modulate performance based on the type of material or strategy used. It is important to note that although numerous studies have addressed the role of the prefrontal cortex in episodic memory, a number of studies have also demonstrated the involvement of a more distributed neural network sustaining this function involving the temporal lobes and parietal cortices. Finally, it is evident that the use of transcranial stimulation techniques might represent a powerful tool not only for investigating the involvement of cerebral areas in a specific cognitive task but also for designing interventional therapies for individuals with memory impairment.     

前额叶损伤患者的视-空间工作记忆改变

目的 探讨前额叶不同亚区损伤患者的视-空间工作记忆障碍.方法 将20例前额叶不同亚区损伤患者以及20名与其人口学资料相匹配的健康人作为被试,采用视觉面孔和视觉空间的延迟匹配任务对上述2组进行视-空间工作记忆测试.结果 与健康对照组(72.9%±6.1%)相比,前额叶腹侧(ventral prefrontal cortex,VPFC)损伤的患者视觉客体工作记忆的正确率(46.4%±11.4%)明显下降,差异有统计学意义(U=1.00,P<0.01);而前额叶背外侧(dorsolateral prefrontal cortex,DLPFC)损伤的患者在视觉客体(50.4%±15.1%)和视觉空间(72.6%±18.6%)工作记忆均有明显损伤,与对照组(72.9%±6.1%、89.4%±10.1%)比较差异均有统计学意义(U=-20.5、59.5,均P<0.01).对左、右前额叶损伤的2组患者进行分析,结果表明2组患者在视觉客体和空间工作记忆正确率的比较差异均无统计学意义.对前额叶亚区进行左右侧比较,2组VPFC患者在视觉客体和视觉空间工作记忆差异均无统计学意义;左侧DLPFC损伤组和右侧DLPFC损伤组在视觉客体工作记忆正确率和视觉面孔工作记忆正确率方面,差异均无统计学意义.结论 前额叶是工作记忆加工的重要脑区,其不仅参与了视觉客体的工作记忆加工过程,同时参与了视觉空间的工作记忆加工,而且对于前额叶不同亚区在视-空间工作记忆加工过程中还存在分离.     

Prospective memory functioning in people with and without brain injury.

Prospective remembering has been relatively underinvestigated in neurological patients. This paper describes a group study in which the prospective memory performance of 36 people with brain injury and 28 control participants is compared. We used a new instrument, the Cambridge Behaviour Prospective Memory Test (CBPMT) to assess prospective memory. This comprises 4 time-based and 4 event-based tasks. Participants were allowed to take notes to help them remember the tasks. The relationships between CBPMT scores, scores on formal tests and subjective reports on memory, attention and executive functioning were analyzed. The key findings were that (1) note-taking significantly benefited prospective memory performance, (2) significant relationships were found between scores on the prospective memory test and scores on tests of memory and executive functions, and (3) participants had more difficulty with the time-based than with the event-based prospective memory tasks. The results suggest that compensatory strategies improve prospective memory functioning; memory for content as well as attention and executive functioning processes are involved in prospective memory; and that time-based tasks are more difficult than event-based tasks because they place higher demands on inhibitory control mechanisms. Discussion focuses on the implications of these results for neuropsychological assessment and rehabilitation.     

Differential components of prospective memory? Evidence from fMRI

Two of the principal components of prospective memory (i.e., remembering to carry out delayed intentions) are recognizing the appropriate context to act ("cue identification") and remembering the action to be performed ("intention retrieval"). In this experiment, the demands on these components were manipulated while measuring brain activity using fMRI to explore whether the two components share a common neural basis. The results showed significant behavioral differences between the cue identification and intention retrieval conditions. However, a consistent pattern of hemodynamic changes was found in both prospective memory conditions in anterior prefrontal cortex (BA 10), with lateral BA 10 activation accompanied by medial BA 10 deactivation. These effects were more pronounced when demands on intention retrieval were high. This is consistent with the hypothesis that anterior prefrontal cortex (area 10) supports the biasing of attention between external events (e.g., identifying the cue amid distracting stimuli) and internal thought processes (i.e., maintaining the intention and remembering the intended actions). Together, the results suggest that whilst cue identification and intention retrieval may be behaviorally separable, they share at least some common neural basis in anterior prefrontal cortex.