Neural networks in the brain involved in memory and recall

Rolls, Edmund T.; Treves, Alessandro

doi:10.1016/s0079-6123(08)60550-6

Cited by 64 publications

(32 citation statements)

References 14 publications

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“…One possible scenario is that hippocampal activity patterns during a given 50% morph trial reflect reinstatements of the entire original learnt representation (e.g., 100% scene A), a process consistent with the operation of a bistable attractor network, and one that might plausibly be viewed to induce participants to choose one response over another. Indeed neural network models have often favored the idea that memories are stored as discrete local attractors (Hopfield,1982; Rolls and Treves,1994), with partial or ambiguous inputs (50% morphs) abruptly inducing the network to occupy one state (e.g., relating to 100% A) or the other (e.g., relating to 100% B) through “global” pattern completion (i.e., output of entire stored pattern). However, the failure of a classifier trained on 50% morphs to correctly assign labels to 100% scenes (see previous analysis), argues strongly against this scenario.…”

Section: Resultsmentioning

confidence: 99%

Decoding representations of scenes in the medial temporal lobes

et al. 2011

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Recent theoretical perspectives have suggested that the function of the human hippocampus, like its rodent counterpart, may be best characterized in terms of its information processing capacities. In this study, we use a combination of high-resolution functional magnetic resonance imaging, multivariate pattern analysis, and a simple decision making task, to test specific hypotheses concerning the role of the medial temporal lobe (MTL) in scene processing. We observed that while information that enabled two highly similar scenes to be distinguished was widely distributed throughout the MTL, more distinct scene representations were present in the hippocampus, consistent with its role in performing pattern separation. As well as viewing the two similar scenes, during scanning participants also viewed morphed scenes that spanned a continuum between the original two scenes. We found that patterns of hippocampal activity during morph trials, even when perceptual inputs were held entirely constant (i.e., in 50% morph trials), showed a robust relationship with participants' choices in the decision task. Our findings provide evidence for a specific computational role for the hippocampus in sustaining detailed representations of complex scenes, and shed new light on how the information processing capacities of the hippocampus may influence the decision making process. © 2011 Wiley Periodicals, Inc.

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Section: Resultsmentioning

confidence: 99%

Decoding representations of scenes in the medial temporal lobes

et al. 2011

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“…In contrast, the reactivation-related expression of zif268 in the DG during rest is relatively preserved, and we hypothesize that this activity is mediated by the backprojection from CA3. This hypothesis is supported by the fact that both computational models (e.g., [32-34]) and experimental evidence (e.g., [34-38]) support CA3 as the most likely source of recapitulation of recent activity patterns. This is thought to stimulate DG either through direct backprojections from CA3c (nearest the hilus), or through indirect projections via mossy cells [39,40].…”

Section: Discussionmentioning

confidence: 97%

Experience-dependent persistent expression of zif268during rest is preserved in the aged dentate gyrus

et al. 2013

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BackgroundAging is typically accompanied by memory decline and changes in hippocampal function. Among these changes is a decline in the activity of the dentate gyrus (DG) during behavior. Lasting memory, however, is thought to also require recapitulation of recent memory traces during subsequent rest – a phenomenon, termed memory trace reactivation, which is compromised in hippocampal CA1 with progressive age. This process has yet to be assessed in the aged DG, despite its prominent role in age-related memory impairment. Using zif268 transcription to measure granule cell recruitment, DG activity in adult and aged animals was assessed both during spatial exploration and as animals remained at rest in the home cage in order to detect potential memory-related replay.ResultsConsistent with the observation of memory trace reactivation in DG, the probability that an individual granule cell transcribes zif268 during rest in the animal’s home cage is increased by recent experience in a novel environment. Surprisingly, a comparable increase was observed in the probability of granule cells in the aged DG expressing zif268 during rest. Moreover, no significant age-related difference was observed in the number of granule cells expressing zif268 during rest. Thus, the number and pattern of granule cell expression of zif268 during rest is preserved in aged animals, despite a significant decline in exploration-related zif268 expression.ConclusionsThese data lead to the hypothesis that the input the aged DG receives from backprojections from CA3 (the region widely hypothesized to mediate reactivation) remains functionally intact despite loss of innervation from the perforant path.

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“…It will be important in future studies to further define the anatomical loci from which the observed pattern completion deficits originate. It would be especially interesting to investigate candidate sites such as the anterior cingular cortex, the temporal cortex and the hippocampus using pharmacological, genetic, and large-scale in vivo recording techniques [11], [41]–[44]. It is also important to assess whether genetic compensation or slow changes in the mutant brain contribute to the observed recall deficits.…”

Section: Discussionmentioning

confidence: 99%

Balanced Dopamine Is Critical for Pattern Completion during Associative Memory Recall

Wang

Shen

et al. 2010

PLoS ONE

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Pattern completion, the ability to retrieve complete memories initiated by partial cues, is a critical feature of the memory process. However, little is known regarding the molecular and cellular mechanisms underlying this process. To study the role of dopamine in memory recall, we have analyzed dopamine transporter heterozygous knockout mice (DAT+/−), and found that while these mice possess normal learning, consolidation, and memory recall under full cue conditions, they exhibit specific deficits in pattern completion under partial cue condition. This form of memory recall deficit in the dopamine transporter heterozygous knockout mice can be reversed by a low dose of the dopamine antagonist haloperidol, further confirming that the inability to retrieve memory patterns is a result of dopamine imbalance. Therefore, our results reveal that a delicate control of the brain's dopamine level is critical for pattern completion during associative memory recall.

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Neural networks in the brain involved in memory and recall

Cited by 64 publications

References 14 publications

Decoding representations of scenes in the medial temporal lobes

Decoding representations of scenes in the medial temporal lobes

Experience-dependent persistent expression of zif268during rest is preserved in the aged dentate gyrus

Balanced Dopamine Is Critical for Pattern Completion during Associative Memory Recall

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