The hippocampus and related neocortical structures in memory transformation

Sekeres, Melanie J.; Winocur, Gordon; Moscovitch, Morris

doi:10.1016/j.neulet.2018.05.006

Cited by 293 publications

(319 citation statements)

References 162 publications

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“…An updated version of the Trace Transformation Theory (TTT) suggests that both the memory details and gist mediated by the pHPC and aHPC, respectively, and schemas mediated by mPFC can all coexist and interact dynamically (Sekeres, Winocur, & Moscovitch, ). The memory from detail‐rich representations to gist‐like or schematic representations is accompanied by corresponding neural representations along the long axis of the hippocampus (Robin & Moscovitch, ; Sekeres et al, ). In sum, our results confirm the important role of hippocampal–neocortical interactions in the dynamics of schematic memory representation (Wang & Morris, ) and provide empirical evidence for the recent TTT (Sekeres et al, ).…”

Section: Discussionmentioning

confidence: 99%

“…Our behavioral results also showed that the schema effect was modulated by retention interval, with a greater schema effect after a 1‐day interval. Further studies are necessary to investigate how the hippocampus and vmPFC activations, as well as their interactions, change over time by including both recent and remote delays (Sekeres et al, ).…”

Section: Discussionmentioning

confidence: 99%

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Interplay of the long axis of the hippocampus and ventromedial prefrontal cortex in schema‐related memory retrieval

Guo

Yang

2019

Hippocampus

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When new information is relevant to prior knowledge or schema, it can be learned and remembered better. Rodent studies have suggested that the hippocampus and ventromedial prefrontal cortex (vmPFC) are important for processing schema‐related information. However, there are inconsistent findings from human studies on the involvement of the hippocampus and its interaction with the vmPFC in schema‐related memory retrieval. To address these issues, we used a human analog of the rodent spatial schema task to compare brain activity during immediate retrieval of paired associations (PAs) in schema‐consistent and schema‐inconsistent conditions. The results showed that the anterior hippocampus was more involved in retrieving PAs in the schema‐consistent condition than in the schema‐inconsistent condition. Connectivity analyses showed that the anterior hippocampus had stronger coupling with the vmPFC when the participants retrieved newly learned PAs successfully in the schema‐consistent (vs. schema‐inconsistent) condition, whereas the coupling of the posterior hippocampus with the vmPFC showed the opposite. Taken together, the results shed light on how the long axis of the hippocampus and vmPFC interact to serve memory retrieval via different networks that differ by schema condition.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Interplay of the long axis of the hippocampus and ventromedial prefrontal cortex in schema‐related memory retrieval

Guo

Yang

2019

Hippocampus

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“…These findings are consistent with reports of functional specialization along the long‐axis of the hippocampus, and its mPFC projections. Anterior hippocampus codes global representations related to the central elements of an event (Poppenk, Evensmoen, Moscovitch, & Nadel, ; Poppenk & Moscovitch, ; Robin & Moscovitch, ; Sekeres, Winocur, & Moscovitch, ). Accordingly, persistent activity in the anterior hippocampus during 7 days retrieval can account for both the increase in mPFC activity, and retrieval of the more schematic version of the memory (Ghosh, Moscovitch, Colella, & Gilboa, ).…”

Section: Discussionmentioning

confidence: 99%

Changes in patterns of neural activity underlie a time‐dependent transformation of memory in rats and humans

et al. 2018

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The dynamic process of memory consolidation involves a reorganization of brain regions that support a memory trace over time, but exactly how the network reorganizes as the memory changes remains unclear. We present novel converging evidence from studies of animals (rats) and humans for the time-dependent reorganization and transformation of different types of memory as measured both by behavior and brain activation. We find that context-specific memories in rats, and naturalistic episodic memories in humans, lose precision over time and activity in the hippocampus decreases. If, however, the retrieved memories retain contextual or perceptual detail, the hippocampus is engaged similarly at recent and remote timepoints. As the interval between the timepoint increases, the medial prefrontal cortex is engaged increasingly during memory retrieval, regardless of the context or the amount of retrieved detail. Moreover, these hippocampal-frontal shifts are accompanied by corresponding changes in a network of cortical structures mediating perceptually-detailed as well as less precise, schematic memories. These findings provide cross-species evidence for the crucial interplay between hippocampus and neocortex that reflects changes in memory representation over time and underlies systems consolidation.

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“…At shorter timescales, recent event‐specific information may be less accessible due to an intervening context shift (DuBrow & Davachi, ; Swallow et al, ). At longer timescales, the details of more remote episodic memories may become less accessible due to time‐dependent memory decay and/or the transformation of those events into more generalized (less detailed) schema representations (Sekeres, Winocur, & Moscovitch, ; Winocur & Moscovitch, ). Thus, more effortful retrieval processes that engage the hippocampus and LPFC may be important when it is desirable to link past occurrences to the present situation.…”

Section: Retroactive Mechanisms Of Binding Sequential Memory Represenmentioning

confidence: 99%

Transcending time in the brain: How event memories are constructed from experience

2019

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Our daily lives unfold continuously, yet when we reflect on the past, we remember those experiences as distinct and cohesive events. To understand this phenomenon, early investigations focused on how and when individuals perceive natural breakpoints, or boundaries, in ongoing experience. More recent research has examined how these boundaries modulate brain mechanisms that support long-term episodic memory. This work has revealed that a complex interplay between hippocampus and prefrontal cortex promotes the integration and separation of sequential information to help organize our experiences into mnemonic events. Here, we discuss how both temporal stability and change in one’s thoughts, goals, and surroundings may provide scaffolding for these neural processes to link and separate memories across time. When learning novel or familiar sequences of information, dynamic hippocampal processes may work both independently from and in concert with other brain regions to bind sequential representations together in memory. The formation and storage of discrete episodic memories may occur both proactively as an experience unfolds. They may also occur retroactively, either during a context shift or when reactivation mechanisms bring the past into the present to allow integration. We also describe conditions and factors that shape the construction and integration of event memories across different timescales. Together these findings shed new light on how the brain transcends time to transform everyday experiences into meaningful memory representations.

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The hippocampus and related neocortical structures in memory transformation

Cited by 293 publications

References 162 publications

Interplay of the long axis of the hippocampus and ventromedial prefrontal cortex in schema‐related memory retrieval

Interplay of the long axis of the hippocampus and ventromedial prefrontal cortex in schema‐related memory retrieval

Changes in patterns of neural activity underlie a time‐dependent transformation of memory in rats and humans

Transcending time in the brain: How event memories are constructed from experience

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