Storage fidelity for sequence memory in the hippocampal circuit

Bayati, Mehdi; Neher, Torsten; Melchior, Jan; Diba, Kamran; Wiskott, Laurenz; Cheng, Sen

doi:10.1371/journal.pone.0204685

Cited by 12 publications

(26 citation statements)

References 117 publications

(130 reference statements)

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“…The hippocampus has been suggested to play a role in the encoding, memorization, and signaling of contexts, especially in extinction learning 3,11 . However, there is no conclusive evidence to rule out that the hippocampus is involved in the renewal phenomenon primarily due to its other well-established role in general-purpose memory storage and retrieval [36][37][38] . In our model, the emergence www.nature.com/scientificreports/ of distinct contextual representations critically depended on experience replay, suggesting that experience replay facilitates the formation of stable memory representations-as predicted by neuroscientific studies 23,39 .…”

Section: Learning Context Representationsmentioning

confidence: 99%

Context-dependent extinction learning emerging from raw sensory inputs: a reinforcement learning approach

Walther

Diekmann

Vijayabaskaran

et al. 2021

Sci Rep

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The context-dependence of extinction learning has been well studied and requires the hippocampus. However, the underlying neural mechanisms are still poorly understood. Using memory-driven reinforcement learning and deep neural networks, we developed a model that learns to navigate autonomously in biologically realistic virtual reality environments based on raw camera inputs alone. Neither is context represented explicitly in our model, nor is context change signaled. We find that memory-intact agents learn distinct context representations, and develop ABA renewal, whereas memory-impaired agents do not. These findings reproduce the behavior of control and hippocampal animals, respectively. We therefore propose that the role of the hippocampus in the context-dependence of extinction learning might stem from its function in episodic-like memory and not in context-representation per se. We conclude that context-dependence can emerge from raw visual inputs.

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Section: Learning Context Representationsmentioning

confidence: 99%

Context-dependent extinction learning emerging from raw sensory inputs: a reinforcement learning approach

Walther

Diekmann

Vijayabaskaran

et al. 2021

Sci Rep

Self Cite

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“…Moreover, due to changes in the synaptic connectivity in the neocortex over time, the hippocampal trace cannot be said to be stably linked to a neocortical activation pattern with a specific representational content. Finally, even though representational content is not preserved by the hippocampal trace, it could be shown on highly trained neural networks, that a reduction of information to only 1-10% of the experiential pattern of activity still enables the network to reliably generate verisimilar representations in the reconstruction phase (Bayati et al 2018;Wiskott (in communication)).…”

Section: Predicting the Past From Minimal Tracesmentioning

confidence: 99%

Predicting the Past from Minimal Traces: Episodic Memory and its Distinction from Imagination and Preservation

Werning

2020

Rev.Phil.Psych.

103

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The paper develops an account of minimal traces devoid of representational content and exploits an analogy to a predictive processing framework of perception. As perception can be regarded as a prediction of the present on the basis of sparse sensory inputs without any representational content, episodic memory can be conceived of as a "prediction of the past" on the basis of a minimal trace, i.e., an informationally sparse, merely causal link to a previous experience. The resulting notion of episodic memory will be validated as a natural kind distinct from imagination. This trace minimalist view contrasts with two theory camps dominating the philosophical debate on memory. On one side, we face versions of the Causal Theory that hold on to the idea that episodic remembering requires a memory trace that causally links the event of remembering to the event of experience and carries over representational content from the content of experience to the content of remembering. The Causal Theory, however, fails to account for the epistemic generativity of episodic memory and is psychologically and information-theoretically implausible. On the other side, a new camp of simulationists is currently forming up. Motivated by empirical and conceptual deficits of the Causal Theory, they reject not only the necessity of preserving representational content, but also the necessity of a causal link between experience and memory. They argue that remembering is nothing but a peculiar form of imagination, peculiar only in that it has been reliably produced and is directed towards an episode of one's personal past. Albeit sharing their criticism of the Causal Theory and, in particular, rejecting its demand for an intermediary carrier of representational content, the paper argues that a causal connection to experience is still necessary to fulfill even the minimal requirements of past-directedness and reliability.

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“…This representational format seems well supported by the hippocampus, which has been shown to be important for storing and retrieving sequences (Agster, Fortin, & Eichenbaum, ; Fortin, Agster, & Eichenbaum, ). Specifically, previous modeling work has suggested that the recurrent network in the hippocampal region CA3 encodes sequences during the experience and replays them during retrieval (Bayati et al, ; Buhry, Azizi, & Cheng, ; Cheng, ; Levy, ; Lisman, ). In summary, we have suggested that a perceptual‐semantic representational network in the neocortex provides higher order representations of the sensory information, while the episodic memory trace only stores the gist of scenes and their temporal evolution.…”

Section: Introductionmentioning

confidence: 99%

Improving sensory representations using episodic memory

2019

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The medial temporal lobe (MTL) is well known to be essential for declarative memory. However, a growing body of research suggests that MTL structures might be involved in perceptual processes as well. Our previous modeling work suggests that sensory representations in cortex influence the accuracy of episodic memory retrieved from the MTL. We adopt that model here to show that, conversely, episodic memory can also influence the quality of sensory representations. We model the effect of episodic memory as (a) repeatedly replaying episodes from memory and (b) recombining episode fragments to form novel sequences that are more informative for learning sensory representations than the original episodes. We demonstrate that the performance in visual discrimination tasks is superior when episodic memory is present and that this difference is due to episodic memory driving the learning of a more optimized sensory representation. We conclude that the MTL can, even if it has only a purely mnemonic function, influence perceptual discrimination indirectly.

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Storage fidelity for sequence memory in the hippocampal circuit

Cited by 12 publications

References 117 publications

Context-dependent extinction learning emerging from raw sensory inputs: a reinforcement learning approach

Context-dependent extinction learning emerging from raw sensory inputs: a reinforcement learning approach

Predicting the Past from Minimal Traces: Episodic Memory and its Distinction from Imagination and Preservation

Improving sensory representations using episodic memory

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