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Pattern separation, the creation of distinct representations of similar inputs, and statistical learning, the rapid extraction of regularities across multiple inputs, have both been linked to hippocampal processing. It has been proposed that there may be functional differentiation within the hippocampus, such that the trisynaptic pathway (entorhinal cortex > dentate gyrus > CA3 > CA1) supports pattern separation, whereas the monosynaptic pathway (entorhinal cortex > CA1) supports statistical learning. To test this hypothesis, we investigated the behavioral expression of these two processes in B. L., an individual with highly selective bilateral lesions in the dentate gyrus that presumably disrupt the trisynaptic pathway. We tested pattern separation with two novel auditory versions of the continuous mnemonic similarity task, requiring the discrimination of similar environmental sounds and trisyllabic words. For statistical learning, participants were exposed to a continuous speech stream made up of repeating trisyllabic words. They were then tested implicitly through a RT-based task and explicitly through a rating task and a forced-choice recognition task. B. L. showed significant deficits in pattern separation on the mnemonic similarity tasks and on the explicit rating measure of statistical learning. In contrast, B. L. showed intact statistical learning on the implicit measure and the familiarity-based forced-choice recognition measure. Together, these results suggest that dentate gyrus integrity is critical for high-precision discrimination of similar inputs, but not the implicit expression of statistical regularities in behavior. Our findings offer unique new support for the view that pattern separation and statistical learning rely on distinct neural mechanisms. [ABSTRACT FROM AUTHOR]

Human thought is prone to biases. Some biases serve as beneficial heuristics to free up limited cognitive resources or improve well-being, but their neurocognitive basis is unclear. One such bias is a tendency to construe events in the distant future in abstract, general terms and events in the near future in concrete, detailed terms. Temporal construal may rely on our capacity to orient toward and/or imagine context-rich future events. We tested 21 individuals with impaired episodic future thinking resulting from lesions to the hippocampus or ventromedial prefrontal cortex (vmPFC) and 57 control participants (aged 45–76 years) from Canada and Italy on measures sensitive to temporal construal. We found that temporal construal persisted in most patients, even those with impaired episodic future thinking, but was abolished in some vmPFC cases, possibly in relation to difficulties forming and maintaining future intentions. The results confirm the fractionation of future thinking and that parts of vmPFC might critically support our ability to flexibly conceive and orient ourselves toward future events. [ABSTRACT FROM AUTHOR]

Keywords: Schema; memory; inferential reasoning; hippocampus; medial prefrontal cortex EN Schema memory inferential reasoning hippocampus medial prefrontal cortex 1 7 7 06/04/20 20200201 NES 200201 Overview In 1932, Bartlett introduced the term "schema" to Psychology and defined it as "an active organization of past reactions, or of past experiences ... " (p. 201). Schema effects on memory and reasoning Three studies examine the extent to which different types of schemas, whether newly or pre-experimentally formed, impact episodic memory. But this is accompanied by higher false alarm rates for schema-consistent items, yielding equivalent memory accuracy for schema-consistent and non-schema information. Notably, such a manipulation improves memory for non-schema items without disrupting memory for schema-consistent items - a pattern apparent in both younger and older adults. [Extracted from the article]

We move our eyes to explore the visual world, extract information, and create memories. The number of gaze fixations--the stops that the eyes make--has been shown to correlate with activity in the hippocampus, a region critical for memory, and with later recognition memory. Here, we combined eyetracking with fMRI to provide direct evidence for the relationships between gaze fixations, neural activity, and memory during scene viewing. Compared to free viewing, fixating a single location reduced: 1) subsequent memory, 2) neural activity along the ventral visual stream into the hippocampus, 3) neural similarity between effects of subsequent memory and visual exploration, and 4) functional connectivity among the hippocampus, parahippocampal place area, and other cortical regions. Gaze fixations were uniquely related to hippocampal activity, even after controlling for neural effects due to subsequent memory. Therefore, this study provides key causal evidence supporting the notion that the oculomotor and memory systems are intrinsically related at both the behavioral and neural level. Individual gaze fixations may provide the basic unit of information on which memory binding processes operate. [ABSTRACT FROM AUTHOR]

Traditionally, studies of spatial memory tend to utilise table-top tasks that focus on new spatial learning, however these in-lab procedures may not be reflective of real world spatial memory or navigation. This study investigated the relationship between self-rated navigation abilities and performance on a naturalistic Internet-based assessment of spatial memory for environments learned long ago. Results indicated that self-rated navigation ability was significantly associated with most of the remote spatial memory metrics. Familiarity with the geographical area tested, as well as frequency of visits, significantly predicted performance on the remote spatial memory measures. These results support the use of internet testing for performance-based navigation abilities in the assessment of remote spatial memory. [ABSTRACT FROM AUTHOR]

Unitization – the fusion of objects into a single unit through an action/consequence sequence – can mitigate relational memory impairments, but the circumstances under which unitization is effective are unclear. Using transverse patterning (TP), we compared unitization (and its component processes of fusion, motion, and action/consequence) with extended practice on relational learning and transfer in older adults and neuropsychological cases with lesions (to varying extents) in the medial prefrontal cortex (mPFC) or hippocampus/medial temporal lobe (HC/MTL). The latter included a person with bilateral HC lesions primarily within the dentate gyrus. For older adults, TP accuracy increased, and transfer benefits were observed, with extended practice and unitization. Broadly, the lesion cases did not benefit from either extended practice or unitization, suggesting the mPFC and dentate gyrus play important roles in relational memory and in unitization. The results suggest that personalized strategy interventions must align with the cognitive and neural profiles of the user. [ABSTRACT FROM AUTHOR]

Objectives: The self-reference effect (SRE), enhanced memory for self-related information, has been studied in healthy young and older adults but has had little investigation in people with age-related memory disorders, such as amnestic mild cognitive impairment (aMCI). Self-referential encoding may help to improve episodic memory in aMCI. Additionally, self-referential processing has been shown to benefit recollection , the vivid re-experiencing of past events, a phenomenon that has been termed the self-reference recollection effect (SRRE; Conway & Dewhurst, 1995). Furthermore, it remains unclear whether the valence of stimuli influences the appearance of the SRE and SRRE. Methods: The current study investigated the SRE and SRRE for trait adjective words in 20 individuals with aMCI and 30 healthy older adult controls. Ninety trait adjective words were allocated to self-reference, semantic, or structural encoding conditions; memory was later tested using a recognition test. Results: While healthy older adults showed a SRE, individuals with aMCI did not benefit from self-referential encoding over and above that of semantic encoding (an effect of "deep encoding"). A similar pattern was apparent for the SRRE; healthy controls showed enhanced recollection for words encoded in the self-reference condition, while the aMCI group did not show specific benefit to recollection for self-referenced over semantically encoded items. No effects of valence were found. Conclusions: These results indicate that while memory for trait adjective words can be improved in aMCI with deep encoding strategies (whether self-reference or semantic), self-referencing does not provide an additional benefit. (JINS , 2018, 24 , 821–832) [ABSTRACT FROM AUTHOR]

ABSTRACT Amnesia is associated with impairments in relational memory, which is critically supported by the hippocampus. By adapting the transitivity paradigm, we previously showed that age-related impairments in inference were mitigated when judgments could be predicated on known pairwise relations, however, such advantages were not observed in the adult-onset amnesic case D.A. Here, we replicate and extend this finding in a developmental amnesic case (N.C.), who also shows impaired relational learning and transitive expression. Unlike D.A., N.C.'s damage affected the extended hippocampal system and diencephalic structures, and does not extend to neocortical areas that are affected in D.A. Critically, despite their differences in etiology and affected structures, N.C. and D.A. perform similarly on the task. N.C. showed intact pairwise knowledge, suggesting that he is able to use existing semantic information, but this semantic knowledge was insufficient to support transitive expression. The present results suggest a critical role for regions connected to the hippocampus and/or medial prefrontal cortex in inference beyond learning of pairwise relations. © 2016 The Authors Hippocampus Published by Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Optimal social functioning occasionally requires concealment of one's emotions in order to meet one's immediate goals and environmental demands. However, because emotions serve an important communicative function, their habitual suppression disrupts the flow of social exchanges and, thus, incurs significant interpersonal costs. Evidence is accruing that the disruption in social interactions, linked to habitual expressive suppression use, stems not only from intrapersonal, but also from interpersonal causes, since the suppressors' restricted affective displays reportedly inhibit their interlocutors' emotionally expressive behaviors. However, expressive suppression use is not known to lead to clinically significant social impairments. One explanation may be that over the lifespan, individuals who habitually suppress their emotions come to compensate for their interlocutors' restrained expressive behaviors by developing an increased sensitivity to nonverbal affective cues. To probe this issue, the present study used functional magnetic resonance imaging (fMRI) to scan healthy older women while they viewed silent videos of a male social target displaying nonverbal emotional behavior, together with a brief verbal description of the accompanying context, and then judged the target's affect. As predicted, perceivers who reported greater habitual use of expressive suppression showed increased neural processing of nonverbal affective cues. This effect appeared to be coordinated in a top-down manner via cognitive control. Greater neural processing of nonverbal cues among perceivers who habitually suppress their emotions was linked to increased ventral striatum activity, suggestive of increased reward value/personal relevance ascribed to emotionally expressive nonverbal behaviors. These findings thus provide neural evidence broadly consistent with the hypothesized link between habitual use of expressive suppression and compensatory development of increased responsiveness to nonverbal affective cues, while also suggesting one explanation for the suppressors' poorer cognitive performance in social situations. Moreover, our results point to a potential neural mechanism supporting the development and perpetuation of expressive suppression as an emotion regulation strategy. [ABSTRACT FROM AUTHOR]

Individuals with developmental amnesia experience compromised development of episodic memory for details of personal life events, believed to relate to changes to the hippocampus after birth. Here we report the very rare discovery of aplasia of the mammillary bodies, hypogenesis of the fornix, and abnormal hippocampal shape and orientation in H.C., a well-documented case of selectively compromised episodic memory development who is the subject of numerous published empirical articles. These anatomical abnormalities are highly suggestive of disrupted extended hippocampal system development very early in gestation, despite an original diagnosis of developmental amnesia and assumed perinatal hypoxia. These findings provide a unique window into the normal function of the mammillary bodies, fornices, and related anterior nuclei of the thalamus bilaterally. The results also encourage re-examination of the pathological basis of developmental amnesia in other cases reported in the literature. [ABSTRACT FROM AUTHOR]

Early cognitive neuroscientific research revealed that the hippocampus is crucial for spatial navigation in rodents, and for autobiographical episodic memory in humans. Researchers quickly linked these streams to propose that the human hippocampus supports memory through its role in representing space, and research on the link between spatial cognition and episodic memory in humans has proliferated over the past several decades. Different researchers apply the term "spatial" in a variety of contexts, however, and it remains unclear what aspect of space may be critical to memory. Similarly, "episodic" has been defined and tested in different ways. Naturalistic assessment of spatial memory and episodic memory (i.e., episodic autobiographical memory) is required to unify the scale and biological relevance in comparisons of spatial and mnemonic processing. Limitations regarding the translation of rodent to human research, human ontogeny, and inter‐individual variability require greater consideration in the interpretation of this literature. In this review, we outline the aspects of space that are (and are not) commonly linked to episodic memory, and then we discuss these dimensions through the lens of individual differences in naturalistic autobiographical memory. Future studies should carefully consider which aspect(s) of space are being linked to memory within the context of naturalistic human cognition. This article is categorized under:Psychology > Memory [ABSTRACT FROM AUTHOR]

The current ubiquity of functional neuroimaging studies, and the importance they have had in elucidating brain function, obscures the fact that much of what we know about brain-behavior relationships derives largely from the study of single- and multiple-patient cases. A major goal of the present review is to describe how single cases continue to uniquely and critically contribute to cognitive neuroscience theory. With several recent examples from the literature, we demonstrate that single cases can both challenge accepted dogma and generate hypotheses and theories that steer the field in new directions. We discuss recent findings from case studies that specify critical functions of the hippocampus in episodic memory and recollection, and clarify its role in nonmnemonic abilities. Although we focus on the hippocampus, we discuss other regions and the occurrence of new associative learning, as well as the involvement of the ventromedial prefrontal and parietal cortices in memory encoding and retrieval. We also describe ways of dealing with the shortcomings of case studies, and emphasize the partnership of patient and neuroimaging methods in constraining neurocognitive models of memory. [ABSTRACT FROM AUTHOR]

Abstract: Qualitative and quantitative reviews of the neuroimaging literature show that overlapping brain regions support theory of mind (ToM) and autobiographical memory (AM). This overlap has been taken to suggest that individuals draw on past personal experiences to infer others’ mental states, but work with amnesic people shows that ToM does not always depend on AM. One variable that may determine the extent to which one relies on AM when inferring another''s thoughts and feelings during ToM is whether that individual is personally known. To test this possibility, participants were scanned with fMRI as they remembered past experiences in response to personal photos (‘AM’ condition) and imagined others’ experiences in response to photos of personally familiar (‘pToM’ condition) and unfamiliar (‘ToM’ condition) others. Spatiotemporal Partial Least Squares was used to identify the spatial and temporal characteristics of neural activation patterns associated with AM, pToM, and ToM. We found that the brain regions supporting pToM more closely resembled those supporting AM relative to ToM involving unfamiliar others, with the greatest degree of overlap within midline regions. A complementary finding was the observation of striking differences between pToM and ToM such that midline regions associated with AM predominated during pToM, whereas more lateral regions associated with social semantic memory predominated during ToM. Overall, this study demonstrates that ToM involves a dynamic interplay between AM and social semantic memory that is biased towards AM when a personally familiar other is the subject of the mental state inference. [Copyright &y& Elsevier]

The ability to navigate in a familiar environment depends on both an intact mental representation of allocentric spatial information and the integrity of systems supporting complementary egocentric representations. Although the hippocampus has been implicated in learning new allocentric spatial information, converging evidence suggests that the posterior parietal cortex (PPC) might support egocentric representations. To date, however, few studies have examined long-standing egocentric representations of environments learned long ago. Here we tested 7 patients with focal lesions in PPC and 12 normal controls in remote spatial memory tasks, including 2 tasks reportedly reliant on allocentric representations (distance and proximity judgments) and 2 tasks reportedly reliant on egocentric representations (landmark sequencing and route navigation; see Rosenbaum, Ziegler, Winocur, Grady, & Moscovitch, 2004). Patients were unimpaired in distance and proximity judgments. In contrast, they all failed in route navigation, and left-lesioned patients also showed marginally impaired performance in landmark sequencing. Patients' subjective experience associated with navigation was impoverished and disembodied conipared with that of the controls. These results suggest that PPC is crucial for accessing remote spatial memories within an egocentric reference frame that enables both navigation and reexperiencing. Additionally, PPC was found to be necessary to implement specific aspects of allocentric navigation with high demands on spontaneous retrieval. [ABSTRACT FROM AUTHOR]

Abstract: A PET study of patients with Alzheimer''s disease (AD) engaged in a delayed match-to-sample face recognition task revealed that performance declines as a function of increasing delay, a pattern accompanied by reduced functional connectivity of prefrontal cortex but increased connectivity of the left amygdala. Here, we characterize the changes in interactions within this amygdalar circuit across the memory delays using structural equation modeling. The magnitude of effective connections was found to be much greater in the patients than in the controls, notably from the left amygdala to left inferior prefrontal cortex, which, in turn, influenced its right homologue. The influence from the amygdala to the left hippocampus, in contrast, was not strong in either group. We interpret this pattern of interactions as possibly reflecting the compensatory recruitment of a dynamic neural network, perhaps involved in implicit emotional processing, in the context of a faulty executive maintenance and retrieval system. [Copyright &y& Elsevier]

Abstract: Autobiographical episodic recall involves active simultaneous generation and binding of various elements that were present during the initial experience. Deficits in this reconstructive process may account for some aspects of retrograde amnesia (RA) for personally experienced events. Constructive and reconstructive processes may involve similar mechanisms. If so, patients with extensive anterograde amnesia (AA) and RA should show deficits in non-recollective cognitive domains, such as imagining events that had never been experienced and recounting non-personal narratives, that presumably rely on constructive and re-constructive processes, respectively. To test these possibilities, patient K.C., who has severe AA and RA for personal episodes, was asked to generate fictional events and to recall and recognize details of well-known fairy tales and bible stories. K.C.’s performance on both tasks was better than expected given his severely impaired autobiographical episodic memory (AM), but significantly worse than that of control participants. K.C. was able to create a skeletal outline for both types of narratives, providing sufficient information to convey their gist, but the narratives were fragmented and lacking in detail. This deficit cannot be explained as resulting entirely from deficient stored semantic knowledge, because K.C. was able to discriminate between true and false details of non-personal semantic narratives on a recognition test, which he cannot do for personal events [Gilboa, A., Winocur, G., Rosenbaum, R.S., Poreh, A., Gao, F., Black, S.E., Westmacott, R., & Moscovitch, M. (2006a). Hippocampal contributions to recollection in retrograde and anterograde amnesia. Hippocampus, 16, 966–980]. Thus, retrograde AM impairment may be viewed as both a loss of information as well as a deficit in reconstructive processes that hamper or prevent the binding of information to generate a cohesive, detail-rich memory. [Copyright &y& Elsevier]

The issue of whether the hippocampus and related structures in the medial-temporal lobe (MTL) play a temporary or permanent role in autobiographical episodic memory remains unresolved. One long-standing belief is that autobiographical memory (AM), like semantic memory, is initially dependent on the MTL but ultimately can be retained and recovered independently of it. However, evidence that hippocampal amnesia results in severe loss of episodic memory for a lifetime of personally experienced events suggests otherwise. To test the opposing views, we conducted detailed investigations of autobiographical episodic memory in people with amnesia resulting from MTL lesions of varying extent. By combining precise quantification of MTL and neocortical volumes with sensitive measures of recollection of one's personal past, we show that the severity of episodic, but not semantic, AM loss is best accounted for by the degree of hippocampal damage and less likely related to additional neocortical compromise. [ABSTRACT FROM AUTHOR]

Preserved remote spatial memory in amnesic people with bilateral hippocampal damage, including the well-studied case K.C., challenges spatial theories, which assume that the hippocampus is needed to support all allocentric spatial representations, old or new. It remains possible, however, that residual hippocampal tissue is functional and contributes to successful performance. Here, we examine brain activity with fMRI during the retrieval of spatial information in K.C. and in healthy controls using landmark and route stimuli from a premorbidly familiar neighborhood that K.C. can navigate normally. In all participants, activity was found in the parahippocampal cortex, but not in the hippocampus itself, during all navigational tasks on which K.C. performs well, even though part of his hippocampus remains viable. The opposite pattern was observed on a house recognition task, which is inconsequential to navigation, and on which K.C. performed poorly. On that task, K.C. recruited the right hippocampus presumably because even 'familiar' houses were treated as novel by him, whereas controls recruited occipitotemporal cortex, including parahippocampal cortex. The distinction between recent and remote memory, therefore, may apply as much to spatial theories of hippocampal function as it does to theories emphasizing the role of the hippocampus in other types of explicit memory. © 2007 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

We review lesion and neuroimaging evidence on the role of the hippocampus, and other structures, in retention and retrieval of recent and remote memories. We examine episodic, semantic and spatial memory, and show that important distinctions exist among different types of these memories and the structures that mediate them. We argue that retention and retrieval of detailed, vivid autobiographical memories depend on the hippocampal system no matter how long ago they were acquired. Semantic memories, on the other hand, benefit from hippocampal contribution for some time before they can be retrieved independently of the hippocampus. Even semantic memories, however, can have episodic elements associated with them that continue to depend on the hippocampus. Likewise, we distinguish between experientially detailed spatial memories (akin to episodic memory) and more schematic memories (akin to semantic memory) that are sufficient for navigation but not for re-experiencing the environment in which they were acquired. Like their episodic and semantic counterparts, the former type of spatial memory is dependent on the hippocampus no matter how long ago it was acquired, whereas the latter can survive independently of the hippocampus and is represented in extra-hippocampal structures. In short, the evidence reviewed suggests strongly that the function of the hippocampus (and possibly that of related limbic structures) is to help encode, retain, and retrieve experiences, no matter how long ago the events comprising the experience occurred, and no matter whether the memories are episodic or spatial. We conclude that the evidence favours a multiple trace theory (MTT) of memory over two other models: (1) traditional consolidation models which posit that the hippocampus is a time-limited memory structure for all forms of memory; and (2) versions of cognitive map theory which posit that the hippocampus is needed for representing all forms of allocentric space in memory. [ABSTRACT FROM AUTHOR]

Abstract: K.C. has been investigated extensively over some 20 years since a motorcycle accident left him with widespread brain damage that includes large bilateral hippocampal lesions, which caused a remarkable case of memory impairment. On standard testing, K.C.''s anterograde amnesia is as severe as that of any other case reported in the literature, including H.M. However, his ability to make use of knowledge and experiences from the time before his accident shows a sharp dissociation between semantic and episodic memory. A good deal of his general knowledge of the world, including knowledge about himself, is preserved, but he is incapable of recollecting any personally experienced events. In displaying such “episodic amnesia,” which encompasses an entire lifetime of personal experiences, K.C. differs from many other amnesic cases. Here, we document for the first time the full extent of K.C.''s brain damage using MRI-based quantitative measurements. We then review the many investigations with K.C. that have contributed to our understanding not only of episodic and semantic memory but also to the development of other aspects of memory theory. These include the distinction between implicit and explicit memory, the prospect of new learning in amnesia, and the fate of recent and remote memory for autobiographical and public events, people, and spatial locations. [Copyright &y& Elsevier]

Conclusions about the duration of hippocampal contributions to our autobiographical record of personal episodes have come under intense scrutiny in recent years. Interpretation is complicated by such factors as extent and site of lesions as well as test sensitivity. We describe the case of an amnesic person, K.C., with large, bilateral hippocampal lesions who figured prominently in the development of theories of remote memory due to his severely impoverished autobiographical memory extending across his entire lifetime. However, the presence of lesions in higher-order visual cortex raises the possibility that K.C.’s retrograde autobiographical amnesia is mediated by loss of long-term visual images, whereas widespread frontal lesions suggest that his impairment may relate to deficits in strategic retrieval rather than storage. Normal performance on an extensive battery of visual imagery tests refutes the imagery loss interpretation. To test for deficits in strategic retrieval, we used a more formal autobiographical memory test requiring generation of personal events under varying levels of retrieval support. However, even with rigorous contextual prompting, K.C. produced few pre-injury recollections; all were schematic, lacking the richness of detail produced by control participants, raising doubt that his deficit is one of retrieval. Findings are discussed in the context of theories concerning the duration of hippocampal-neocortical interactions in supporting autobiographical re-experiencing. The approach we used to investigate the effects of different lesions on memory provides a framework for dealing with other patients who present with an interesting functional deficit whose neuroanatomical source is difficult to specify due to widespread lesions. [Copyright &y& Elsevier]

The role of the hippocampus in recent spatial memory has been well documented in patients with damage to this structure, but there is now evidence that the hippocampus may not be needed for the storage and recovery of a spatial layout that was experienced long before injury. Such preservation may rely, instead, on a network of dissociable, extra-hippocampal regions implicated in topographical orientation. Using functional magnetic resonance imaging (fMRI), we investigated this hypothesis in healthy individuals with extensive experience navigating in a large-scale urban environment (downtown Toronto). Participants were scanned as they performed mental navigation tasks that emphasized different types of spatial representations. Tasks included proximity judgments, distance judgments, landmark sequencing, and blocked-route problem-solving. The following regions were engaged to varying degrees depending on the processing demands of each task: retrosplenial cortex, believed to be involved in assigning directional significance to locales within a relatively allocentric framework; medial and posterior parietal cortex, concerned with processing space within egocentric coordinates during imagined movement; and regions of prefrontal cortex, present in tasks heavily dependent on working memory. In a second, event-related experiment, a distinct area of inferotemporal cortex was revealed during identification of familiar landmarks relative to unknown buildings in addition to activation of many of those regions identified in the navigation tasks. This result suggests that familiar landmarks are strongly integrated with the spatial context in which they were experienced. Importantly, right medial temporal lobe activity was observed, its magnitude equivalent across all tasks, though the core of the activated region was in the parahippocampal gyrus, barely touching the hippocampus proper. © 2004 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

The hippocampus may have a time-limited role in memory, being needed only until information is permanently stored elsewhere, or this region may permanently represent long-term allocentric spatial information or cognitive maps in memory. To test these ideas, we investigated remote spatial memory in K.C., a patient with bilateral hippocampal lesions and amnesia for autobiographical events. In his spatial knowledge, general aspects were preserved, but details were lost, a pattern that resembled his memory loss in other domains. K.C. performed normally on allocentric spatial tests of his neighborhood and the world. He had difficulty, however, in recognizing and identifying non-salient neighborhood landmarks, and in recognizing city locations on world maps. This suggests that the hippocampus is not crucial for maintenance and retrieval of remotely formed spatial representations of major landmarks, routes, distances and directions, but is necessary for specifying location details, regardless of when they were acquired. [ABSTRACT FROM AUTHOR]

Don's influence reverberates through the hundreds of trainees who have passed through the Rotman Research Institute, many of whom are now leading investigators in their own right. Don influenced the field by astute clinical observations of disruptions in these phenomena in patients, and he translated these into testable hypotheses. Don Stuss was one of a kind. [Extracted from the article]

As clear memories transport us back into the past, the brain also revives prior patterns of neural activity, a phenomenon known as neural reactivation. While growing evidence indicates a link between neural reactivation and typical variations in memory performance in healthy individuals, it is unclear how and to what extent reactivation is disrupted by a memory disorder. The current study characterizes neural reactivation in a case of amnesia using Multivoxel Pattern Analysis (MVPA). We tested NC, an individual with developmental amnesia linked to a diencephalic stroke, and 19 young adult controls on a functional magnetic resonance imaging (fMRI) task during which participants viewed and recalled short videos multiple times. An encoding classifier trained and tested to identify videos based on brain activity patterns elicited at perception revealed superior classification in NC. The enhanced consistency in stimulus representation we observed in NC at encoding was accompanied by an absence of multivariate repetition suppression, which occurred over repeated viewing in the controls. Another recall classifier trained and tested to identify videos during mental replay indicated normal levels of classification in NC, despite his poor memory for stimulus content. However, a cross-condition classifier trained on perception trials and tested on mental replay trials—a strict test of reactivation—revealed significantly poorer classification in NC. Thus, while NC's brain activity was consistent and stimulus-specific during mental replay, this specificity did not reflect the reactivation of patterns elicited at perception to the same extent as controls. Fittingly, we identified brain regions for which activity supported stimulus representation during mental replay to a greater extent in NC than in controls. This activity was not modeled on perception, suggesting that compensatory patterns of representation based on generic knowledge can support consistent mental constructs when memory is faulty. Our results reveal several ways in which amnesia impacts distributed patterns of stimulus representation during encoding and retrieval. • Neural pattern classification of shown repeated videos was superior in amnesic person • Repetition suppression during repeated viewing was absent, unlike in controls • During recall, reactivation of neural patterns from perception was reduced • Video-specific neural pattern elicited at recall engaged alternative brain regions [ABSTRACT FROM AUTHOR]

We use gaze fixations to freely explore the visual world1, and the amount of visual exploration is related to subsequent memory2. The hippocampus plays a crucial role in forming memories. An open question for investigation is whether the hippocampus binds visual information across individual gaze fixations3. We recently found that the hippocampus was activated more strongly when an increasing number of fixations were deployed to face stimuli, and this relationship between hippocampal activation and visual exploration was weaker in older adults, who also showed weaker memory effects. These findings suggested that the hippocampus may form memory representations by binding visual information from individual fixations4,5. However, given that participants' eye movements were measured in natural viewing tasks in previous studies4,5, the evidence to date is correlational in nature. To experimentally manipulate the relationship between visual exploration and hippocampal activity, in the current fMRI study we asked participants to either freely explore scenes or fixate on a single location. We found that the hippocampus was activated more strongly, and the memory performance was better, in the free than fixed viewing condition, and differences between the conditions were stronger when participants were processing meaningful scenes compared to meaningless scrambled images. In this talk, I will describe our recent studies that support the idea that the hippocampus binds visual memory representations online, across gaze fixations. This line of research calls for researchers to consider individual gaze fixations, instead of individual stimuli, as the basic unit of information on which the (hippocampal) memory system works. [ABSTRACT FROM AUTHOR]

The Self-Reference Effect (SRE), enhanced memory for self-related information, has been established in healthy young and older adults but has had limited study in age-related memory disorders such as amnestic Mild Cognitive Impairment (aMCI). Additionally, the majority of SRE studies have been conducted using trait adjective paradigms, which lack ecological validity; memory for narrative information has real-world importance and has been shown to decline in healthy aging and, to a greater extent, in aMCI. The present study investigated whether self-referential processing promotes memory for narrative information in healthy aging and, for the first time, in aMCI. The promotion of recollection (vivid re-experiencing of an event) through self-referential processing, termed the Self-Reference Recollection Effect (SRRE; Conway and Dewhurst, 1995), was also examined, as was the potential impact of material valence on the SRE. Twenty individuals with aMCI and thirty healthy older controls encoded short narratives under self-reference, semantic, and structural conditions. Memory for narrative details was subsequently tested. Results indicated a SRE for narrative information in both aMCI and healthy control groups on a recognition memory test. The SRRE was found in healthy controls and individuals with aMCI. Material valence did not impact the SRE in either group. The SRE appears to be powerful enough to circumvent loss of hippocampal function in aMCI, possibly due to the multimodal nature of narrative information. Findings from this study highlight the potential of the SRE as an effective intervention tool for improving memory for narrative information in aMCI. • Episodic memory declines in aging and amnestic Mild Cognitive Impairment (aMCI). • Memory may benefit from self-related processing (self-reference effect). • Real-world narratives were encoded in relation to self, semantic, or surface features. • Finding of self-reference effect in aging and aMCI, possibly via vivid re-experiencing. • Self-reference effect may circumvent loss of hippocampal function. [ABSTRACT FROM AUTHOR]

Evidence suggests that individual hippocampal subfields are preferentially involved in various memory‐related processes. Here, we demonstrated dissociations in these memory processes in two unique individuals with near‐selective bilateral damage within the hippocampus, affecting the dentate gyrus (DG) in case BL and the cornu ammonis 1 (CA1) subfield in case BR. BL was impaired in discriminating highly similar objects in memory (i.e., mnemonic discrimination) but exhibited preserved overall recognition of studied objects, regardless of similarity. Conversely, BR demonstrated impaired general recognition. These results provide evidence for the DG in discrimination processes, likely related to underlying pattern separation computations, and the CA1 in retention/retrieval. [ABSTRACT FROM AUTHOR]

ObjectiveMethodResultsConclusionsPast research has shown that self-reported everyday strategy use and task-specific strategy use are related to associative memory performance in aging. Understudied is the relationship between these types of strategy use, whether they predict associative memory performance, and how this may differ across genders.A sample of older adults (N = 566, 53% female, ages 60–80) completed this online study. Study measures included 1. Multifactorial Memory Questionnaire (MMQ) Strategy Use subscale, a self-report measure of everyday strategy use, 2. Face-Name Task (FNT), a measure of associative memory, and 3. self-initiated number and types of strategies used on the FNT. Analyses examined the interrelationships among all study measures and their relative contributions to FNT performance while accounting for intraindividual factors.Participants who reported using more strategies on the FNT performed better than those who used fewer or no strategies; those who reported using at least three strategies and relating FNT to past experience performed best. Women outperformed men on the FNT but did not differ in task-specific strategy use. Participants who reported using no strategies on the FNT had lower MMQ Strategy Use scores. A multiple regression analysis indicated that female gender and using at least two task strategies were significant predictors of greater FNT performance.The results indicate that task-specific strategy use relates more to associative memory performance than to everyday strategy use, but neither accounts for the female advantage in FNT performance. Findings encourage querying task-specific strategy use to contextualize age-related associative memory decline. [ABSTRACT FROM AUTHOR]

Humans have the capacity to form new memories of events that are, at times, highly similar to events experienced in the past, as well as the capacity to integrate and associate new information within existing knowledge structures. The former process relies on mnemonic discrimination and is believed to depend on hippocampal pattern separation, whereas the latter is believed to depend on generalization signals and conceptual categorization supported by the neocortex. Here, we examine whether and how the ventromedial prefrontal cortex (vMPFC) supports discrimination and generalization on a widely used task that was primarily designed to tax hippocampal processes. Ten individuals with lesions to the vMPFC and 46 neurotypical control participants were administered an adapted version of the mnemonic similarity task [Stark, S. M., Yassa, M. A., Lacy, J. W., & Stark, C. E. L. A task to assess behavioral pattern separation (BPS) in humans: Data from healthy aging and mild cognitive impairment. Neuropsychologia, 51, 2442–2449, 2013], which assesses the ability to distinguish previously learned images of everyday objects (targets) from unstudied, highly similar images (lures) and dissimilar images (foils). Relative to controls, vMPFC-lesioned individuals showed intact discrimination of lures from targets but a propensity to mistake studied targets and similar lures for dissimilar foils. This pattern was accompanied by inflated confidence despite low accuracy when responding to similar lures. These findings demonstrate a more general role of the vMPFC in memory retrieval, rather than a specific role in supporting pattern separation. [ABSTRACT FROM AUTHOR]

The unprecedented efforts to minimize the effects of the COVID-19 pandemic introduce a new arena for human face recognition in which faces are partially occluded with masks. Here, we tested the extent to which face masks change the way faces are perceived. To this end, we evaluated face processing abilities for masked and unmasked faces in a large online sample of adult observers (n = 496) using an adapted version of the Cambridge Face Memory Test, a validated measure of face perception abilities in humans. As expected, a substantial decrease in performance was found for masked faces. Importantly, the inclusion of masks also led to a qualitative change in the way masked faces are perceived. In particular, holistic processing, the hallmark of face perception, was disrupted for faces with masks, as suggested by a reduced inversion effect. Similar changes were found whether masks were included during the study or the test phases of the experiment. Together, we provide novel evidence for quantitative and qualitative alterations in the processing of masked faces that could have significant effects on daily activities and social interactions. [ABSTRACT FROM AUTHOR]

Does the tendency to adjust appraisals of ourselves in the past and future in order to maintain a favourable view of ourselves in the present require episodic memory? A developmental amnesic person with impaired episodic memory (HC) was compared with two groups of age-matched controls on tasks assessing the Big Five personality traits and social competence in relation to the past, present and future. Consistent with previous research, controls believed that their personality had changed more in the past 5 years than it will change in the next 5 years (i.e. the end-of-history illusion), and rated their present and future selves as more socially competent than their past selves (i.e. social improvement illusion), although this was moderated by self-esteem. Despite her lifelong episodic memory impairment, HC also showed these biases of temporal self-appraisal. Together, these findings do not support the theory that the temporal extension of the self-concept requires the ability to recollect richly detailed memories of the self in the past and future. [ABSTRACT FROM AUTHOR]

Autobiographical remembering and future imagining overlap in their underlying psychological and neurological mechanisms. The hippocampus and surrounding regions within the medial temporal lobes (MTL), known for their role in forming and maintaining autobiographical episodic memories, are also thought to play an essential role in fictitious and future constructions. Amnesic individuals with bilateral hippocampal damage cannot reconstruct their past personal experiences and also have severe deficits in the ability to construct coherent fictitious or future narratives. However, it is not known whether this impairment reflects a failure to generate details from autobiographical episodic memory to populate personal narratives or an inability to bind such details into coherent narratives. We show that four individuals with hippocampal damage and episodic amnesia can construct narratives when the relevant details of the story are provided in a picture book and that their narratives maintain overall coherence on several measures. These findings indicate that individuals with hippocampal damage can bind details into coherent narratives when details are available to them. We conclude that the hippocampal system instead likely plays a role in the generation of details from which narratives are constructed. [ABSTRACT FROM AUTHOR]

The cover image is based on the Advanced Review What about "space" is important for episodic memory? by Carina L. Fan et al., https://doi.org/10.1002/wcs.1645. [ABSTRACT FROM AUTHOR]

The article describes the result of the examination of the relation between the theory of mind (ToM) to episodic memory and autonoetic consciousness by administering objective ToM tests to participants without autonoetic abilities. Participants, K. C. and M. L., lost their ability to consciously recollect personal happenings from their own lives as a result of severe traumatic brain injury. Both K. C. and M. L. loss stands in complete contrast to their preserved ability to think of personal and public facts learned before they suffered brain injuries. The authors stress that the two cases do not shed any light on the extent to which fully functioning autonoetic ability is necessary for the development of ToM because K. C. and M. L. may have acquired ToM ability premorbidly.

The ability to recognize the prior occurrence of objects can operate effectively even in the absence of successful recollection of episodic contextual detail about a relevant past object encounter. The pertinent process, familiarity assessment, is typically probed in humans with recognition-memory tasks that include an experimentally controlled study phase for a list of items. When meaningful stimuli such as words or pictures of common objects are employed, participants must judge familiarity with reference to the recent experimental encounter rather than their lifetime of autobiographical experience, which may have involved hundreds or thousands of exposures across numerous episodic contexts. Humans can, however, also judge the cumulative familiarity of objects concepts they have encountered over their lifetime. At present, little is known about the cognitive and neural mechanisms that support this ability. Here, we tested an individual (NB) with a rare left anterior temporal-lobe lesion that included perirhinal cortex but spared the hippocampus, who had previously been found to exhibit selective impairments in familiarity assessment on verbal recognition-memory tasks. As NB exhibits normal recollection abilities, her case presents a unique opportunity to examine potential links between both types of familiarity. In Experiment 1, we demonstrated that NB's impairment in making recognition judgments affects cumulative frequency judgments for exposure to concept names in a recent study episode. Experiments 2 and 3 revealed, with a task borrowed from the semantic-memory literature, that NB's impairments do indeed extend to abnormalities in judging cumulative lifetime familiarity for object concepts. These abnormalities were not limited to verbal processing, and were present even when pictures were offered as additional cues. Moreover, they showed sensitivity to concept structure as reflected in semantic feature norms; we only observed them for judgments on object concepts with high feature overlap. In Experiment 4, we found that an amnesic patient (HC) with previously established deficits in autobiographical recollection, due to a selective lesion of the extended hippocampal system, does not exhibit any abnormalities in assessing lifetime familiarity. Together, these findings provide support for a functional link between the assessment of recent changes in familiarity, as probed with experimental study-test paradigms, and cumulative lifetime familiarity based on autobiographical experience accrued outside the laboratory. They argue in favor of the notion that familiarity is closely related to the representation of concept knowledge, likely through computations in perirhinal cortex. [ABSTRACT FROM AUTHOR]

Objectives To determine whether severity of episodic prospection impairment in medial temporal lobe ( MTL) amnesia is reduced by the types of cues that are used to elicit personal future episodes and, if so, whether episodic memory impairment is similarly affected. Design Multiple case study of five individuals with MTL amnesia and healthy control participants. Methods Participants were administered two tests of episodic prospection: A commonly used Galton- Crovitz task that uses generic cues (e.g., lemon) and a novel task that includes specific, personally meaningful cues referring to planned or plausible future events (e.g., granddaughter's recital). Narratives were scored for episodic detail using the Autobiographical Interview protocol ( Levine et al., 2002), which distinguishes between internal (episodic) details and external (non-episodic) details. Results Results showed that specific, personally meaningful cues led to an appreciable reduction of episodic memory and prospection impairment in three of the amnesic cases tested. Clinical benefit from more structured, self-related cues may depend on factors such as extent of MTL damage or general severity of episodic memory and prospection impairment, highlighting the importance of methodological approaches to neuropsychological research that treat each case on an individual basis. Conclusions In cases of mild-moderate amnesia, specific, personal cues afford more detailed episodic remembering and prospective imagining than individual cue words. Practitioner points Previous reports of episodic prospection impairment in medial temporal lobe ( MTL) amnesia might misrepresent an individual case's true prospective abilities, Specific cues drawn from a patient's everyday life have greater ecological validity than the more typical generic cues used to elicit episodic prospection and can aid some individuals with MTL amnesia in the ability to imagine future experiences, Assessment and rehabilitation tools for MTL amnesic populations should attempt to minimize broad, open-ended questions and instead provide more structured and personally meaningful cues to guide responses, Further research is needed to determine case-specific characteristics that best predict benefit from specific, personal cues. These might include extent of MTL damage and overall severity of episodic memory and prospection impairment. [ABSTRACT FROM AUTHOR]

Constructing autobiographical events involves an initial phase of event selection, in which a memory or imagined future event is initially brought to mind, followed by a phase of elaboration, in which an individual accesses detailed knowledge specific to the event. While considerable research demonstrates the importance of the medial temporal lobes (MTL) in the later phase, its role in initial event selection is unknown. The present study is the first to investigate the role of the MTL in event selection by assessing whether individuals with MTL lesions select qualitatively different events for remembering and imagining than matched control participants. To do so, we created “event captions” that reflected the type of events selected for an autobiographical event narrative task by four individuals with MTL amnesia and control counterparts. Over 450 online raters assessed these event captions on qualitative dimensions known to vary with autobiographical recall (frequency, significance, emotionality, imageability, and uniqueness). Our critical finding was that individuals with MTL amnesia were more prone to select events that were rated as more frequently occurring than healthy control participants. We interpret this finding as evidence that people with impaired episodic memory from MTL damage compensate for their compromised ability to recall detailed information by relying more heavily on semantic memory processes to select generalized events. We discuss the implications for theoretical models of memory and methodological approaches to studying autobiographical memory. [ABSTRACT FROM AUTHOR]

Social network size has been associated with complex socio-cognitive processes (e.g., memory, perspective taking). Supporting this idea, recent neuroimaging studies in healthy adults have reported a relationship between social network size and brain volumes in regions related to memory and social cognition (e.g., hippocampus, amygdala). Lesion-deficit studies in neurological patients are rare and have been inconclusive due to differences in participant sampling and measurement. The present study uses a multiple case study approach. We investigated patients with focal damage to the hippocampus and/or amygdala (two neural structures thought to be critical for social networks), and examined the patients' social network size, loneliness, and life satisfaction relative to a non-injured comparison group. Patients with amygdalar damage had smaller social networks and reported higher levels of loneliness and lower life satisfaction, on average, than comparison participants. Patients with damage to the hippocampus reported more friends than the comparison participants, but did not differ in their ratings of loneliness or life satisfaction. This lesion study offers new evidence that the amygdala is critical for social networks, life satisfaction, and reduced loneliness. [ABSTRACT FROM AUTHOR]

Face masks, which became prevalent across the globe during the COVID-19 pandemic, have had a negative impact on face recognition despite the availability of critical information from uncovered face parts, especially the eyes. An outstanding question is whether face-mask effects would be attenuated following extended natural exposure. This question also pertains, more generally, to face-recognition training protocols. We used the Cambridge Face Memory Test in a cross-sectional study (N = 1,732 adults) at six different time points over a 20-month period, alongside a 12-month longitudinal study (N = 208). The results of the experiments revealed persistent deficits in recognition of masked faces and no sign of improvement across time points. Additional experiments verified that the amount of individual experience with masked faces was not correlated with the mask effect. These findings provide compelling evidence that the face-processing system does not easily adapt to visual changes in face stimuli, even following prolonged real-life exposure. [ABSTRACT FROM AUTHOR]

ABSTRACT Several recent studies have compared episodic and spatial memory in neuroimaging paradigms in order to understand better the contribution of the hippocampus to each of these tasks. In the present study, we build on previous findings showing common neural activation in default network areas during episodic and spatial memory tasks based on familiar, real-world environments (Hirshhorn et al. (2012) Neuropsychologia 50:3094-3106). Following previous demonstrations of the presence of functionally connected sub-networks within the default network, we performed seed-based functional connectivity analyses to determine how, depending on the task, the hippocampus and prefrontal cortex differentially couple with one another and with distinct whole-brain networks. We found evidence for a medial prefrontal-parietal network and a medial temporal lobe network, which were functionally connected to the prefrontal and hippocampal seeds, respectively, regardless of the nature of the memory task. However, these two networks were functionally connected with one another during the episodic memory task, but not during spatial memory tasks. Replicating previous reports of fractionation of the default network into stable sub-networks, this study also shows how these sub-networks may flexibly couple and uncouple with one another based on task demands. These findings support the hypothesis that episodic memory and spatial memory share a common medial temporal lobe-based neural substrate, with episodic memory recruiting additional prefrontal sub-networks. © 2014 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Widespread vaccination is necessary to minimize or halt the effects of many infectious diseases, including COVID-19. Stagnating vaccine uptake can prolong pandemics, raising the question of how we might predict, prevent, and correct vaccine hesitancy and unwillingness. In a multinational sample (N = 4,452) recruited from 13 countries that varied in pandemic severity and vaccine uptake (July 2021), we examined whether short-sighted decision-making as exemplified by steep delay discounting—choosing smaller immediate rewards over larger delayed rewards—predicts COVID-19 vaccination status. Delay discounting was steeper in unvaccinated individuals and predicted vaccination status over and above demographics or mental health. The results suggest that delay discounting, a personal characteristic known to be modifiable through cognitive interventions, is a contributing cause of differences in vaccine compliance. [ABSTRACT FROM AUTHOR]

Abstract: Functional magnetic resonance imaging (fMRI) was used to compare brain activity during the retrieval of coarse- and fine-grained spatial details and episodic details associated with a familiar environment. Long-time Toronto residents compared pairs of landmarks based on their absolute geographic locations (requiring either coarse or fine discriminations) or based on previous visits to those landmarks (requiring episodic details). An ROI analysis of the hippocampus showed that all three conditions activated the hippocampus bilaterally. Fine-grained spatial judgments recruited an additional region of the right posterior hippocampus, while episodic judgments recruited an additional region of the right anterior hippocampus, and a more extensive region along the length of the left hippocampus. To examine whole-brain patterns of activity, Partial Least Squares (PLS) analysis was used to identify sets of brain regions whose activity covaried with the three conditions. All three comparison judgments recruited the default mode network including the posterior cingulate/retrosplenial cortex, middle frontal gyrus, hippocampus, and precuneus. Fine-grained spatial judgments also recruited additional regions of the precuneus, parahippocampal cortex and the supramarginal gyrus. Episodic judgments recruited the posterior cingulate and medial frontal lobes as well as the angular gyrus. These results are discussed in terms of their implications for theories of hippocampal function and spatial and episodic memory. [Copyright &y& Elsevier]

In previous work, we showed that adult rats that were reared socially for 3 months in a complex (village) environment retained allocentric spatial memory for that environment following hippocampal lesions (Winocur et al., () Nat Neurosci 8:273-275). In the present series of experiments, we showed that 3 months of postoperative rearing did not confer the same benefits (Experiment 1), although hippocampal groups, with or without rearing experience, exhibited spatial learning after extensive training (Experiments 1 and 2). Experiment 3 showed that as little as 2 weeks of preoperative rearing in the village was sufficient to retain acquired spatial memories after hippocampal lesions. Probe testing revealed that, although rats with hippocampal lesions exhibited remarkably good memory for preoperatively learned locations in the village, they were impaired when changes in task demands required flexible use of existing spatial representations. In a direct test of flexibility (Experiment 4), preoperatively reared rats were administered a blocked-routes task in the original learning environment, in which on designated trials, a barrier was placed across one of the direct paths to the goal compartment. On encountering the barrier, control rats consistently selected the next most direct route, whereas rats with hippocampal lesions, despite using spatial strategies, made more errors and took longer to find the goal. The present results confirm that allocentric spatial memories can survive hippocampal damage but they are schematic in nature and less cohesive than those associated with cognitive maps in intact brains. As well, there was evidence that, although different processes are involved in their formation, the schematic memories that were acquired preoperatively and survived hippocampal lesions are essentially the same as those laboriously formed postoperatively after extensive training. © 2010 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

This work examined whether semantically relevant schemas could facilitate learning in the transverse patterning (TP) task, which requires participants to learn the value of each stimulus in relation to the stimulus with which it is paired (e.g., A wins over B, B wins over C, C wins over A). Younger and older adults received the standard TP in isolation (alone condition), with additional sessions (practice condition), or with 2 TP sessions, which used familiar stimuli with known relations (e.g., rock–paper–scissors, semantic condition). Accuracy improved when training was provided within the context of a previously known relational framework, beyond the benefits obtained with extended practice with the task. When levels of education and vocabulary scores were considered as covariates, age-related deficits in accuracy were observed in the alone and practice conditions but were eliminated in the semantic condition. Extended practice and appealing to prior knowledge improved explicit awareness for the stimulus contingencies for each age-group. Thus, age-related deficits in learning relations among items may be remediated using existing relational information within semantic memory as an analog for new learning. [ABSTRACT FROM PUBLISHER]

Abstract: The effect of aging on remote spatial memory was tested in a group of 2-year-old rats (VR-O) that, as young adults, were reared for 3 months in a complex ’village’ environment. The VR-O rats exhibited significant savings in finding the locations of specific reward compartments within the village, relative to a group of old rats (VNR-O) experiencing the village for the first time. The VNR-O rats were also impaired, relative to naive young rats, in learning the reward locations. Probe tests indicated that the VR-O rats retained allocentric spatial memory for the environment and were not using sensory or other non-spatial cues to guide behaviour. Overall, the results indicate that the aged rats experienced a decline in the ability to learn and remember detailed spatial relationships and that the VR-O group''s successful performance on the remote spatial memory test was guided by a form of schematic memory that captured the essential features of the village environment. The potential contribution of the hippocampus to the pattern of lost and spared learning and memory observed in the aged rats was discussed. [Copyright &y& Elsevier]

We examined whether alternate systems compensate for deficient ones to process relations in amnesia. Transverse patterning (TP), a test of relating items to one another in memory, is reliably impaired in amnesia and has played a central role in testing hippocampal function. We facilitated successful TP in amnesia by providing familiar stimuli with semantically meaningful relationships. Tapping semantic knowledge allowed TP to be solved via extrahippocampal structures. Our work shows that by framing a situation as meaningful we can engage alternate neural systems to compensate for impairments. © 2007 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Lesions restricted to the hippocampal formation and/or extended hippocampal system (hippocampal formation, fornix, mammillary bodies, and anterior thalamic nuclei) can disrupt conscious recollection in anterograde amnesia, while leaving familiarity-based memory relatively intact. Familiarity may be supported by extra-hippocampal medial temporal lobe (MTL) structures. Within-task dissociations in recognition memory best exemplify this distinction in anterograde amnesia. The authors report for the first time comparable dissociations within recognition memory in retrograde amnesia. An amnesic patient (A.D.) with bilateral fornix and septal nuclei lesions failed to recognize details pertaining to personal past events only when recollection was required, during recognition of episodic details. His intact recognition of generic and semantic details pertaining to the same events was ascribed to intact familiarity processes. Recollective processes in the controls were reflected by asymmetrical Receiver's Operating Characteristic curves, whereas the patient's Receiver's Operating Characteristic was symmetrical, suggesting that his inferior recognition performance on episodic details was reliant on familiarity processes. Anterograde and retrograde memories were equally affected, with no temporal gradient for retrograde memories. By comparison, another amnesic person (K.C.) with extensive MTL damage (involving extra-hippocampal MTL structures in addition to hippocampal and fornix lesions) had very poor recognition and no recollection of either episodic or generic/semantic details. These data suggest that the extended hippocampal system is required to support recollection for both anterograde and retrograde memories, regardless of their age. © 2006 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]