Decreased fidelity of mnemonic representations plays a critical role in age-related episodic memory deficits, yet the brain mechanisms underlying such reductions remain unclear. Using functional and structural neuroimaging, we examined how changes in two key nodes of the posterior-medial network, the hippocampus and the angular gyrus (AG), might underpin loss of memory precision in older age. Healthy young and older adults completed a memory task that involved reconstructing object features on a continuous scale. Investigation of blood-oxygen-level-dependent (BOLD) activity during retrieval revealed an age-related reduction in activity reflecting successful recovery of object features in the hippocampus, whereas trial-wise modulation of BOLD signal by graded memory precision was diminished in the AG. Gray matter volume of the AG further predicted individual differences in memory precision in older age, beyond likelihood of successful retrieval. These findings provide converging evidence for a role of functional and structural integrity of the AG in constraining the fidelity of episodic remembering in older age, yielding new insights into parietal contributions to age-related episodic memory decline.

The qualities of remembered experiences are often used to inform "reality monitoring" judgments, our ability to distinguish real and imagined events. Previous experiments have tended to investigate only whether reality monitoring decisions are accurate or not, providing little insight into the extent to which reality monitoring may be affected by qualities of the underlying mnemonic representations. We used a continuous-response memory precision task to measure the quality of remembered experiences that underlie two different types of reality monitoring decisions: self/experimenter decisions that distinguish actions performed by participants and the experimenter and imagined/perceived decisions that distinguish imagined and perceived experiences. The data revealed memory precision to be associated with higher accuracy in both self/experimenter and imagined/perceived reality monitoring decisions, with lower precision linked with a tendency to misattribute self-generated experiences to external sources. We then sought to investigate the possible neurocognitive basis of these observed associations by applying brain stimulation to a region that has been implicated in precise recollection of personal events, the left angular gyrus. Stimulation of angular gyrus selectively reduced the association between memory precision and self-referential reality monitoring decisions, relative to control site stimulation. The angular gyrus may, therefore, be important for the mnemonic processes involved in representing remembered experiences that give rise to a sense of self-agency, a key component of "autonoetic consciousness" that characterizes episodic memory.

Our recollections of past experiences can vary in both the number of specific event details accessible from memory and the precision with which such details are reconstructed. Prior neuroimaging evidence suggests the success and precision of episodic recollection to rely on distinct neural substrates during memory retrieval. In contrast, the specific encoding mechanisms supporting later memory precision, and whether they differ from those underlying successful memory formation in general, are currently unknown. Here, we combined continuous measures of memory retrieval with model-based analyses of behavioral and neuroimaging data to tease apart the encoding correlates of successful memory formation and mnemonic precision. In the MRI scanner, participants encoded object-scene displays and later reconstructed features of studied objects using a continuous scale. We observed overlapping encoding activity in inferior prefrontal and posterior perceptual regions to predict both which object features were later remembered versus forgotten and the precision with which they were reconstructed from memory. In contrast, hippocampal encoding activity significantly predicted the precision, but not overall success, of subsequent memory retrieval. The current results align with theoretical accounts proposing the hippocampus to be critical for representation of high-fidelity associative information and suggest a contribution of shared cortical encoding mechanisms to the formation of both accessible and precise memory representations.

Episodic memory declines with older age, but it is unresolved whether this decline reflects reduced probability of successfully retrieving information from memory, or decreased precision of the retrieved information. Here, we used continuous measures of episodic memory retrieval in combination with computational modelling of participants’ retrieval errors to distinguish between these two potential accounts of age-related memory deficits. In three experiments, young and older participants encoded stimuli displays consisting of everyday objects varying along different perceptual features (e.g., location, colour and orientation) in a circular space. At test, participants recreated the features of studied objects using a continuous response dial. Across all three experiments, we observed age-related declines in the precision of episodic memory retrieval, whereas age differences in retrieval success were limited to the most challenging task condition. Reductions in mnemonic precision were evident for retrieval of both item-based and contextual information, and persisted after controlling for age-related decreases in the fidelity of perception and working memory. The findings highlight impoverished precision of memory representations as one factor contributing to age-related episodic memory loss, and suggest that the cognitive and neural changes associated with older age can differentially affect distinct aspects of episodic retrieval.

Recognition memory can be faulty. Participants sometimes incorrectly judge unseen stimuli as seen before (false alarms, FAs), or seen stimuli as not seen (misses). However, the sources of these memory errors remain poorly understood. This study combines an identical(old)/similar/new recognition memory task with a memory precision task to explore sources of recognition memory errors. The results demonstrate that while FAs to similar but unseen items are associated with surprisingly high memory precision, incorrect classification of identical items as ‘similar’ is associated with a marked decline in memory precision. Lastly, incorrect ‘new’ ratings to both identical and similar items showed most severely decreased memory precision, over and above that seen for other memory misclassifications. These results suggest that misses are due to memory decay processes, while FAs stem from recollection-based interference between stimuli. The findings lay the groundwork to explore specific memory deficits in different populations.

Schemas are knowledge structures that allow us to make efficient judgments about the world without the cost of memorizing every detail of previous experiences. It has long been known that schemas can enhance long-term memory for related information. The usefulness of schemas, however, critically depends on their adaptability: how flexibly a schema can be updated according to changing environmental conditions. Prior consolidation of a schema supports new learning of schema-consistent information. Yet, the effect of consolidation on inconsistent information, and how schemas may be subsequently updated, are not well understood. It is difficult to track the dynamic updating of knowledge structures with traditional memory measures. Here, using a continuous-report paradigm, we were able to show that schematization increases incrementally with consolidation and that the strength with which schemas are initially established predicts schema-guided responding in a later test. Critically, schema updating in response to inconsistent information was more pronounced in a group which was given time to consolidate compared to a group that was not given time to consolidate. Importantly, the later group reverted back to the no longer relevant schema, indicating that systematic bias towards old information, rather than increased forgetting, underlies reduced memory for schema-inconsistent information.

One of the primary contributors to forgetting is interference from overlapping memories. Intuitively, this suggests-and prominent theoretical models argue-that memory interference is best avoided by encoding overlapping memories as if they were unrelated. It is therefore surprising that reactivation of older memories during new encoding has been associated with reduced memory interference. Critically, however, prior studies have not directly established why reactivation reduces interference. Here, we first developed a behavioral paradigm that isolates the negative influence that overlapping memories exert during memory retrieval. We then show that reactivating older memories during the encoding of new memories dramatically reduces this interference cost at retrieval. Finally, leveraging multiple fMRI decoding approaches, we show that spontaneous reactivation of older memories during new encoding leads to integration of overlapping memories and, critically, that integration during encoding specifically reduces interference between overlapping, and otherwise competing, memories during retrieval.

Schemas are higher-level knowledge structures that store an abstraction of multiple previous experiences. They allow us to retain a multitude of information, but without the cost of storing every detail. Schemas are believed to be relatively stable, but occasionally have to be updated to remain useful in the face of changing environmental conditions. Once a schema is consolidated, schema updating has been proposed to be the result of a prediction error (PE) based learning mechanism, similar to the updating of less complex knowledge. However, for schema memory this hypothesis has so far been difficult to test since the tools to track modifications to abstracted memory schemas have not been sensitive enough. Moreover, existing research on electrophysiological correlates of updating have focused on short-term belief updating tasks. Here I am using EEG and continuous memory measures recorded during the encoding of new schema consistent and inconsistent material to test the behavioural and neural correlates of schema updating. Schema updating was assessed in a memory test 24 hours after encountering inconsistent information, demonstrating the long-term effect of such PE-based learning. I observed a stronger relationship between behavioural PE and schema updating measures for inconsistent compared to consistent material, in line with the idea that more updating is required when a schema changes. Moreover, the P3 EEG signal tracked both the PE at the time of learning, as well as the updating of the memory schema one day later in the inconsistent condition. These results demonstrate that schema updating in the face of inconsistent information is indeed driven by PE-based mechanisms, and that similar neural mechanisms underlie the updating of consolidated long-term schemas and short-term belief structures.

Memory retrieval can strengthen, but also distort memories. Parietal cortex is a candidate region involved in retrieval-induced memory changes as it reflects retrieval success and represents retrieved content. Here, we conducted an fMRI experiment to test whether different forms of parietal reactivation predict distinct consequences of retrieval. Subjects studied associations between words and pictures of faces, scenes, or objects, and then repeatedly retrieved half of the pictures, reporting the vividness of the retrieved pictures ("retrieval practice"). On the following day, subjects completed a recognition memory test for individual pictures. Critically, the test included lures highly similar to studied pictures. Behaviorally, retrieval practice increased both hit and false alarm (FA) rates to similar lures, confirming a causal influence of retrieval on subsequent memory. Using pattern similarity analyses, we measured two different levels of reactivation during retrieval practice: generic "category-level" reactivation and idiosyncratic "item-level" reactivation. Vivid remembering during retrieval practice was associated with stronger category- and item-level reactivation in parietal cortex. However, these measures differentially predicted subsequent recognition memory performance: whereas higher category-level reactivation tended to predict FAs to lures, item-level reactivation predicted correct rejections. These findings indicate that parietal reactivation can be decomposed to tease apart distinct consequences of memory retrieval.

S OF OPEN PAPERS ORAL PRESENTATIONS (in order of presentation) The importance of the ventromedial prefrontal cortex for memory for life-like events C. M. Bird , C. S. Oedekoven , P. Raykov , J. L. Keidel , K. Bromis , M Raczek 2 1 School of Psychology, University of Sussex, UK; 2 Old Age Psychiatry, Sussex Partnership NHS Foundation Trust, Worthing, UK Episodic memory recruits a large network of brain regions. In particular, the ventromedial prefrontal cortex (vmPFC) has been associated with linking incoming information with prior knowledge in order to comprehend and remember events. We collected MRI data and tested memory for short films in 73 patients attending Memory Assessment Clinics and 20 age-matched healthy controls. Memory for short films was strongly associated with clinical diagnoses of Alzheimer's disease, Mild Cognitive Impairment and “no impairment” in the patient cohort. Voxel-based morphometry revealed grey-matter volume correlations with memory performance throughout the "core episodic retrieval network". grey matter volume in the vmPFC was specifically correlated with ability to remember the films, after controlling for performance on the Doors and People Test. Furthermore, when watching the films, brain activity in the vmPFC was synchronised across individuals with high memory performance but not across lowperforming individuals. These findings implicate the vmPFC in memory for life-like events, particularly during memory encoding. Core regions for syntactic processing? A tDCS study on the language network M. Garraffa , A Sedda 1 1 Department of Psychology, School of Social Sciences, Heriot-Watt University UK tDCS was adopted to inhibit Broca’s (BA 44/45) or the LT area (BA22) in two groups of adults, during a sentences comprehension task, with the aim of investigating the role of these language hubs in syntactic processing. During both stimulation and sham conditions, participants performed a comprehension task, comprising 40 sentences divided in 4 syntactic structures. All participants performed accordingly to the syntactic complexity of the task, as shown by the main effect of Type of Sentence (p < .001). Importantly, we also found a significant interaction between Group and Stimulation (p = .033), driven by the effect of cathodal stimulation in Broca’s area, which worsen performance. The findings of our study support Broca's area core functional engagement for syntactic processing. The Sex Factor: Is the assessor equitable to male and female infants during developmental assessments? Andrew Chew , Serena Counsell , Mary Rutherford , Alexandra Bonthrone , Chiara Nosarti 1 1 Centre for the Developing Brain, King's College London, St Thomas' Hospital, London, UK Using FaceReader, the assessor’s facial expressions were measured during a full developmental assessment. The aim was to compare possible differences in the assessor's responses towards male and female toddlers. 29 video-recordings of assessor’s face were analysed (12 for male; 17 for female infants). Six basic facial expressions were measured: happiness, sadness, anger, surprise, fear, disgust. 'Neutral' denotes when no distinct facial expression was detected. The most commonly detected facial expression was neutral (mean 42%), followed by happiness (29.1%), sadness (13.0%), and surprise (7.4%). Analysis of facial expression showed no difference when assessing male or female infants, except for sadness (14.5% male, 12.0% females, T-Test, p=0.013); this frequency difference is small and significance could be due to small sample size. AUTUMN 2018 PROGRAMME & ABSTRACTS The fate of 1st and 2nd languages in bilingual patients with semantic dementia R. Ellajosyula , J. Narayanan 1, K. Patterson 2 1 Departments of Neurology, Manipal and Annasawmy Mudaliar Hospitals, Bangalore, India; 2 Department of Clinical Neurosciences and MRC CBU, University of Cambridge, UK Objectives: A large proportion of the world’s population is bilingual, yet almost nothing is known about the nature of the deterioration in the different languages of bilingual patients with neurodegenerative diseases that compromise language. Methods: Following clinical diagnosis and confirmation with structural MRI, 13 bilingual patients with semantic dementia (SD) were assessed over several sessions on the same tests of naming and word comprehension in their first (L1) and second (L2) languages . Their results were compared to test scores from 21 matched healthy controls. L1 in all participants was one of the main languages spoken in southern India. L2 encompassed a variety of languages, including English for 7 patients. Results: As expected in well-established SD, all patients had significantly impaired naming and comprehension abilities even in their L1; but performance was dramatically lower in L2, even for the patients with high ratings of premorbid proficiency in both languages. Furthermore, the specific items yielding correct naming responses in a patient’s L2 were a virtually perfect subset of correct responses to the same items in his or her L1, and the same was true for the test of word comprehension. Conclusions: The striking disadvantage for L2 in SD indicates that a bilingual’s less-preferred language is more vulnerable to neurodegeneration. The dramatic item-specific correspondence between L2 and L1 suggests that the two languages in a bilingual share a common semantic network in the brain. The influence of aetiology and cognitive reserve on cognitive performance in patients with focal frontal and non-frontal lesions S. E. MacPherson , M. Allerhand , S. Gharooni , D. Smirni , T. Shallice , E. Chan , L. Cipolotti 3 1 Human Cognitive Neuroscience, Department of Psychology, University of Edinburgh, Edinburgh, UK; 2 Department of Psychology, University of Edinburgh, Edinburgh, UK; 3 Department of Neuropsychology, National Hospital for Neurology and Neurosurgery, London, UK; 4 Dipartimento di Scienze Psicologiche, Pedagogiche e della Formazione, Università degli Studi di Palermo, Palermo, Italy; 6 Institute of Cognitive Neuroscience, University College London, UK; 7 International School for Advanced Sudies (SISSA-ISAS), Trieste, Italy The Cognitive Reserve (CR) hypothesis suggests that premorbid efficacy, aptitude and flexibility of cognitive processing can aid the brain’s ability to cope with change or damage. Our previous work demonstrates that age and literacy attainment predict the cognitive performance of frontal patients on frontal-executive measures. However, it remains unknown whether CR can also predict the cognitive performance of non-frontal patients. In the current study, we examined the independent effects of two CR proxies, education and NART IQ, as well as age and lesion group (non-frontal versus frontal) on measures of executive function, intelligence, speed of information processing and naming. One hundred and twenty-two patients with unilateral lesions in the frontal lobes and 168 patients with unilateral lesions in nonfrontal, posterior brain regions were retrospectively recruited for the study. We fitted multiple linear regression models for each of the cognitive measures and found that NART IQ predicted executive, intelligence and naming performance. Education did not independently predict performance on any of our cognitive tests. We also found that age significantly predicted performance on the executive tests and speed of processing. Lesion group only predicted intelligence. These results suggest that age and literacy attainment play independent roles in predicting cognitive performance. However, the relationship between CR proxies and focal brain damage does not differ in the context of frontal and non-frontal lesions. Neglect Dyslexia as a Word-Centred Impairment: A Single Case Study M. Moore , N Demeyere 1 1 Cognitive Neurology Centre, Department of Experimental Psychology, University of Oxford, UK Neglect dyslexia is a neuropsychological syndrome characterised by consistently lateralised errors when reading. This case study investigates patient AB who demonstrated right neglect dyslexia in the AUTUMN 2018 PROGRAMME & ABSTRACTS absence of visuospatial neglect. AB completed the Oxford Cognitive Screen and an original assessment designed to investigate the effects of orientation and content manipulations on reading. AB was found to commit neglect dyslexic errors affecting the terminal letters of individual words when reading normal, vertical, and mirror-reflected words, regardless of where these terminal letters were presented in space. AB was unimpaired when reading numbers and demonstrated a qualitatively different error pattern when reading pseudo-words. These results both replicate and extend previous findings supporting a content-specific, word-centred explanation of neglect dyslexia. Neuropsychological Assessment and Amyotrophic Lateral Sclerosis: A Systems Approach Clinic to Controlled Trial T. Burke 1, 2, , O. Hardiman , N. Pender 1,2 1 Beaumont Hospital, Dublin, Ireland; 2 Academic Unit of Neurology, Trinity College Dublin, Ireland; 3 School of Psychology, University College Dublin, Dublin, Ireland. Cognitive impairment and behavioural dysfunction is an integral part of Amyotrophic Lateral Sclerosis (ALS) for many patients. This presentation reports a series of studies which investigated cognition, behavioural features and phenotypes, service engagement, and clinico-demographics of patients with ALS, to assess the relationship with caregiver burden. This research employed a crosssectional population based design with longitudinal components, where patients with ALS underwent neuropsychological assessment and behavioural profiling (n=317), and their primary caregiver completed a semi-structure interview (n=100). This work outlines distinct cognitive and behavioural phenotypes associated with ALS, and how first attendance at a clinic can predict caregiver burden in a population based cohort of patients, which has led to the development of

21 Memory schemas allow us to make efficient judgments about the world without the 22 cost of memorizing every detail of previous experiences. It has long been known that 23 schemas can enhance long-term memory for related information. The usefulness of 24 schemas, however, critically depends on their adaptability: how flexibly a schema can 25 be updated according to changing environmental conditions. It is difficult to track the 26 dynamic updating of individual memories with traditional memory measures. Using a 27 continuous report paradigm we show that schematization effects increase with 28 consolidation, that a group which was given time to consolidate showed increased 29 evidence of schema updating compared to a group that was not given time to 30 consolidate, and that the strength with which schemas are initially established 31 predicts to what degree participants let schemas guide their responses in a later test. 32 These results provide a novel perspective on the dynamic knowledge structures that 33 guide everyday behaviour. 34 The term ‘schema’ refers to complex knowledge structures within memory that 35 connect overlapping elements of information. Schemas are believed to support the 36 retention of information derived from a multitude of individual episodic memories, and 37 to help us generalize from previous experiences and predict the outcomes of future 38 events (e.g., Ghosh & Gilboa, 2014; van Kesteren, Ruiter, Fernández, & Henson, 39 2012). It has long been known that memory schemas are beneficial for the 40 remembering of schema congruent versus incongruent information (Bartlett, 1932; 41 Bransford & Johnson, 1972). This effect has been attributed to both enhanced deep 42 encoding (Staresina, Gray, & Davachi, 2009) and increases in schema-consistent 43 guesses (Rojahn & Pettigrew, 1992; Sakamoto & Love, 2004). During encoding, 44 schema congruency can accelerate the onset of memory formation processes 45 (Packard et al., 2017). During retrieval, the automatic activation of related information 46 in response to a retrieval cue enhances retrieval success (van Kesteren et al., 2012). 47 Thus, schemas contribute to memory performance by influencing processing during 48 both encoding and retrieval. 49 50 The development of knowledge structures such as schemas relies heavily on 51 consolidation, the process by which memories stabilize over time (Nadel & 52 Moscovitch, 1997; Squire & Alvarez, 1995). Consolidated schemas provide us with a 53 framework to predict outcomes according to our knowledge of events that fit the 54 existing schema. Models of reinforcement learning regard the drive to optimally 55 predict outcomes of the world as one of the main sources of learning (cf. Schultz, 56 Dayan, & Montague, 1997). Erroneous predictions due to inconsistent information 57 (i.e., unexpected outcomes) may be one source of such learning (Sutton & Barto, 58 1998). Similar mechanisms have been postulated in the long-term memory literature: 59 predictive coding models of memory are based on the idea that learning results from 60 divergences between experience-based predictions and observed outcomes 61 (Henson & Gagnepain, 2010; cf. Krawczyk, Fernández, Pedreira, & Boccia, 2017). 62 63 For an organism to be able to make predictions based on schematized memories, a 64 consolidated schema needs to exist to guide those predictions. Findings consistent 65 with this view have recently been reported by Richards and colleagues (2014), who 66 used a water-maze task in which mice had to learn to swim to platforms that 67 clustered according to a location schema. The authors found that a 30vs. 1-day 68 consolidation period augmented the formation of schemas: mice were better at 69 finding schema-consistent platforms with the longer compared to the shorter delay 70 after learning a location schema. Furthermore, consolidated schema memories 71 increased sensitivity to information that was inconsistent with the schema: mice 72 initially displayed higher errors, but more learning of this information was evident in a 73 later final test. That is, the authors found stronger updating of consolidated schemas 74 in the face of inconsistent information. Moreover, the authors hypothesized that the 75 area responsible for the updating of schemas would be the medial prefrontal cortex 76 (MPFC). Consistently, they found that pharmacological inhibition of MPFC impaired 77 updating of the schema. In line with this finding by Richards et al., human fMRI and 78 patient work has also postulated a role of (ventro-) medial PFC in schematic 79 memories (e.g., Brod & Shing, 2018; Ghosh, Moscovitch, Melo Colella, & Gilboa, 8

Increasing recent research has sought to understand the recollection impairments experienced by individuals with autism spectrum disorder (ASD). Here, we tested whether these memory deficits reflect a reduction in the probability of retrieval success or in the precision of memory representations. We also used functional magnetic resonance imaging (fMRI) to study the neural mechanisms underlying memory encoding and retrieval in ASD, focusing particularly on the functional connectivity of core episodic memory networks. Adults with ASD and typical control participants completed a memory task that involved studying visual displays and subsequently using a continuous dial to recreate their appearance. The ASD group exhibited reduced retrieval success, but there was no evidence of a difference in retrieval precision. fMRI data revealed similar patterns of brain activity and functional connectivity during memory encoding in the 2 groups, though encoding-related lateral frontal activity predicted subsequent retrieval success only in the control group. During memory retrieval, the ASD group exhibited attenuated lateral frontal activity and substantially reduced hippocampal connectivity, particularly between hippocampus and regions of the fronto-parietal control network. These findings demonstrate notable differences in brain function during episodic memory retrieval in ASD and highlight the importance of functional connectivity to understanding recollection-related retrieval deficits in this population.

Much evidence from distinct lines of investigation indicates the involvement of angular gyrus (AnG) in the retrieval of both episodic and semantic information, but the region's precise function and whether that function differs across episodic and semantic retrieval have yet to be determined. We used univariate and multivariate fMRI analysis methods to examine the role of AnG in multimodal feature integration during episodic and semantic retrieval. Human participants completed episodic and semantic memory tasks involving unimodal (auditory or visual) and multimodal (audio-visual) stimuli. Univariate analyses revealed the recruitment of functionally distinct AnG subregions during the retrieval of episodic and semantic information. Consistent with a role in multimodal feature integration during episodic retrieval, significantly greater AnG activity was observed during retrieval of integrated multimodal episodic memories compared with unimodal episodic memories. Multivariate classification analyses revealed that individual multimodal episodic memories could be differentiated in AnG, with classification accuracy tracking the vividness of participants' reported recollections, whereas distinct unimodal memories were represented in sensory association areas only. In contrast to episodic retrieval, AnG was engaged to a statistically equivalent degree during retrieval of unimodal and multimodal semantic memories, suggesting a distinct role for AnG during semantic retrieval. Modality-specific sensory association areas exhibited corresponding activity during both episodic and semantic retrieval, which mirrored the functional specialization of these regions during perception. The results offer new insights into the integrative processes subserved by AnG and its contribution to our subjective experience of remembering. SIGNIFICANCE STATEMENT Using univariate and multivariate fMRI analyses, we provide evidence that functionally distinct subregions of angular gyrus (AnG) contribute to the retrieval of episodic and semantic memories. Our multivariate pattern classifier could distinguish episodic memory representations in AnG according to whether they were multimodal (audio-visual) or unimodal (auditory or visual) in nature, whereas statistically equivalent AnG activity was observed during retrieval of unimodal and multimodal semantic memories. Classification accuracy during episodic retrieval scaled with the trial-by-trial vividness with which participants experienced their recollections. Therefore, the findings offer new insights into the integrative processes subserved by AnG and how its function may contribute to our subjective experience of remembering.

Long-term memory encoding depends critically on effective processing of incoming information. The degree to which participants engage in effective encoding can be indexed in electroencephalographic (EEG) data by studying event-related potential (ERP) subsequent memory effects. The current study investigated ERP correlates of memory success operationalised with two different measures-memory selectivity and global memory-to assess whether previously observed ERP subsequent memory effects reflect focused encoding of task-relevant information (memory selectivity), general encoding success (global memory), or both. Building on previous work, the present study combined an attention switching paradigm-in which participants were presented with compound object-word stimuli and switched between attending to the object or the word across trials-with a later recognition memory test for those stimuli, while recording their EEG. Our results provided clear evidence that subsequent memory effects resulted from selective attentional focusing and effective top-down control (memory selectivity) in contrast to more general encoding success effects (global memory). Further analyses addressed the question of whether successful encoding depended on similar control mechanisms to those involved in attention switching. Interestingly, differences in the ERP correlates of attention switching and successful encoding, particularly during the poststimulus period, indicated that variability in encoding success occurred independently of prestimulus demands for top-down cognitive control. These results suggest that while effects of selective attention and selective encoding co-occur behaviourally their ERP correlates are at least partly dissociable.

A network of brain regions have been linked with episodic memory retrieval, but limited progress has been made in identifying the contributions of distinct parts of the network. Here, we utilized continuous measures of retrieval to dissociate three components of episodic memory: retrieval success, precision, and vividness. In the fMRI scanner, participants encoded objects that varied continuously on three features: color, orientation, and location. Participants memory was tested by having them recreate the appearance of the object features using a continuous dial, and continuous vividness judgments were recorded. Retrieval success, precision, and vividness were dissociable both behaviorally and neurally: successful versus unsuccessful retrieval was associated with hippocampal activity, retrieval precision scaled with activity in the angular gyrus, and vividness judgments tracked activity in the precuneus. The ability to dissociate these components of episodic memory reveals the benefit afforded by measuring memory on a continuous scale, allowing functional parcellation of the retrieval network.

The hippocampal memory system is thought to alternate between two opposing processing states: encoding and retrieval. When present experience overlaps with past experience, this creates a potential tradeoff between encoding the present and retrieving the past. This tradeoff may be resolved by memory integration—that is, by forming a mnemonic representation that links present experience with overlapping past experience. Here, we used fMRI decoding analyses to predict when – and establish how – past and present experiences become integrated in memory. In an initial experiment, we alternately instructed subjects to adopt encoding, retrieval or integration states during overlapping learning. We then trained across-subject pattern classifiers to ‘read out’ the instructed processing states from fMRI activity patterns. We show that an integration state was clearly dissociable from encoding or retrieval states. Moreover, trial-by-trial fluctuations in decoded evidence for an integration state during learning reliably predicted behavioral expressions of successful memory integration. Strikingly, the decoding algorithm also successfully predicted specific instances of spontaneous memory integration in an entirely independent sample of subjects for whom processing state instructions were not administered. Finally, we show that medial prefrontal cortex and hippocampus differentially contribute to encoding, retrieval, and integration states: whereas hippocampus signals the tradeoff between encoding vs. retrieval states, medial prefrontal cortex actively represents past experience in relation to new learning.

Three experiments investigated the impact of cognitive control on current performance and later memory in task switching. Participants first switched between object and word classification tasks, performed on picture-word stimuli that each appeared only once, then were tested for their recognition memory of these items. Each experiment replicated the recent finding that task switching results in reduced selectivity in later memory for task-relevant over task-irrelevant items. Top-down control was manipulated through varying the time available for advance task preparation (Experiment 1), the freedom of choice over which task to perform (Experiment 2), and the availability of reward incentives (Experiment 3). For each manipulation, more effective top-down control during task switching was associated with increased selectivity in memory for task-relevant information. These findings shed new light on the role of cognitive control in long-term memory encoding, in particular supporting an interactive model in which long-term memory reflects the enduring traces of perceptual and cognitive processes that operate under the selective influence of top-down control.

Discussions of the contributions of neuroimaging research to psychology have emphasized two distinct but related aims: to identify the neural basis of cognitive processes and, conversely, to use emerging neuroimaging data to inform cognitive theories (Coltheart, 2004; Henson, 2005; Poldrack, 2006). Here we review progress toward these aims in functional magnetic resonance imaging (fMRI) studies of task switching. In common with most cognitive neuroscience research, we take localization of function in the brain to be a necessary foundational step, but our real focus is the use of neuroimaging data to shed new light on the cognitive mechanisms of task switching. We therefore begin with a brief overview of brain regions that are consistently activated during task switching—presenting a new meta-analysis of 34 published fMRI studies—but devote the bulk of the chapter to an exploration of the implications of these neuroimaging findings for current theories of cognitive control in task switching. Our discussion addresses four questions. The first is whether neuroimaging evidence supports theories emerging from behavioral studies of task switching. We focus in particular on the developing consensus that the switch cost—the drop in performance seen when people switch tasks as compared with repeatedly perform the same task—reflects a complex interplay between top-down cognitive control and competitive interactions between tasks (Kiesel et al., 2010; Monsell, 2003; Vandierendonck, Liefooghe, & Verbruggen, 2010). The second question is whether neuroimaging evidence provides support for the often-implicit assumption that “task switching …

Cognitive control and memory are fundamentally intertwined, but interactions between the two have only recently received sustained research interest. In the study reported here, we used a novel paradigm to investigate how control influences memory encoding and, conversely, how memory measures can provide new insight into flexible cognitive control. Participants switched between classifying objects and words, then were tested for their recognition memory of items presented in this task-switching phase. Task switching impaired memory for task-relevant information but actually improved memory for task-irrelevant information, which indicates that control demands reduced the selectivity of memory encoding rather than causing a general memory decline. Recognition memory strength provided a robust trial-by-trial measure of the effectiveness of cognitive control that "predicted" earlier task-switching performance. It also revealed a substantial influence of bottom-up factors on between-task competition, but only on trials in which participants had to switch from one type of classification to the other. Collectively, our findings illustrate how cognitive control and bottom-up factors interact to simultaneously influence both current performance and future memory.