Hippocampal CA1 Subregion as a Context Decoder

Barrientos, Sebastián A.; Tiznado, Vicente

doi:10.1523/jneurosci.1107-16.2016

Cited by 15 publications

(13 citation statements)

References 20 publications

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“…A strikingly high proportion (close to 25%) of the CA1 neurons show differential activity upon the presentation of the correct or of a non-matching element of a memorized odor sequence (Allen et al, 2016). This finding inspired a model (Barrientos and Tiznado, 2016) where the learned sequence is replayed by the trisynaptic loop, while the actual element presented is represented by the temporoammonic FIGURE 6 | Processing of the phase precessing signals by the recurrent CA3 network. (A) Signals that are subsequent along a theta cycle but arrive within a defined window of time can be made coincident by the recurrent collateral CA3 network.…”

Section: The Entorhinal Cortex → Dentate Gyrus Processing: Pattern Comentioning

confidence: 99%

Episodic Memories: How do the Hippocampus and the Entorhinal Ring Attractors Cooperate to Create Them?

Kovács

2020

Front. Syst. Neurosci.

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The brain is capable of registering a constellation of events, encountered only once, as an episodic memory that can last for a lifetime. As evidenced by the clinical case of the patient HM, memories preserving their episodic nature still depend on the hippocampal formation, several years after being created, while semantic memories are thought to reside in neocortical areas. The neurobiological substrate of one-time learning and lifelong storing in the brain, that must exist at the cellular and circuit level, is still undiscovered. The breakthrough is delayed by the fact that studies jointly investigating the rodent hippocampus and entorhinal cortex are mostly targeted at understanding the spatial aspect of learning. Here, we present the concept of an entorhinal cortical module, termed EPISODE module, that could explain how the representations of different elements constituting episodic memories can be linked together at the stage of encoding. The new model that we propose here reconciles the structural and functional observations made in the entorhinal cortex and explains how the downstream hippocampal processing organizes the representations into meaningful sequences.

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Section: The Entorhinal Cortex → Dentate Gyrus Processing: Pattern Comentioning

confidence: 99%

Episodic Memories: How do the Hippocampus and the Entorhinal Ring Attractors Cooperate to Create Them?

Kovács

2020

Front. Syst. Neurosci.

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“…Unlike CA3, CA1 lacks strong recurrent collaterals. Therefore, CA1 might integrate information from two distinct pathways (Barrientos and Tiznado, 2016; Knierim and Neunuebel, 2016). One is the direct layer III EC projection to CA1, which is suggested to provide the organism’s current state.…”

Section: Discussionmentioning

confidence: 99%

Hippocampus maintains a flexible and coherent map under reward flavor-landmark cue conflict

Nair

Roy

2021

Preprint

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Animals predominantly use salient visual cues (landmarks) for efficient navigation over other sensory modalities. When the relative position of the visual cues is altered, the hippocampal population exhibits heterogeneous responses and constructs context-specific spatial maps. Another critical factor that can strongly modulate spatial representation is the presence of reward. Reward features can drive behavior and are known to bias spatial attention. However, it is unclear whether reward flavors are used for spatial reference in the presence of distal cues and how the hippocampus population dynamics changes when the association between reward flavors and distal cues is altered. We investigated these questions by recording place cells from the CA1 while the rats ran in an environment with the conflicting association between reward flavors and distal cues. We report that the hippocampal place cells coherently and dynamically bind to reward flavors or distal cues across sessions, but not simultaneously suggesting the use of a single spatial map. We found that place cells maintained their spatial offset in the cue conflict conditions, thus showing a robust spatial coupling featuring an attractor-like property in the CA1. When the textures were added on the track, the coherency of the CA1 is degraded, as the hippocampus showed a heterogeneous response and weak spatial coupling of co-recorded cells suggesting a break away from the attractor network. These results indicate that reward flavors alone may be used for spatial reference but may not cause sufficient input difference to create context-specific spatial maps in the CA1.

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“…A strikingly high proportion (close to 25%) of the CA1 neurons show differential activity upon the presentation of the correct or of a nonmatching element of a memorized odor sequence (Allen et al, 2016). This finding inspired a model (Barrientos and Tiznado, 2016) where the learned sequence is replayed by the trisynaptic loop, while the actual element presented is represented by the temporoammonic pathway and the CA1 decides about the correct or incorrect nature of that particular element.…”

Section: The Ca3 → Ca1 Processing: Integration Comparison and Directmentioning

confidence: 96%

Episodic memories: how do the hippocampus and the entorhinal ring attractors cooperate to create them?

Kovács

2020

Preprint

View full text Add to dashboard Cite

The brain is capable of registering a constellation of events, encountered only once, as an episodic memory that can last for a lifetime. As evidenced by the clinical case of the patient HM, memories preserving their episodic nature still depend on the hippocampal formation, several years after being created, while semantic memories are thought to reside in neocortical areas. The neurobiological substrate of one-time learning and life-long storing in the brain, that must exist at the cellular and circuit level, is still undiscovered. The breakthrough is delayed by the fact that studies jointly investigating the rodent hippocampus and entorhinal cortex are mostly targeted at understanding the spatial aspect of learning. Here we present the concept of an entorhinal cortical module, termed EPISODE module, that could explain how the representations of different elements constituting episodic memories can be linked together. The new model that we propose here reconciles the structural and functional observations made in the entorhinal cortex and explains how the downstream hippocampal processing organizes the representations into meaningful sequences.

show abstract

Hippocampal CA1 Subregion as a Context Decoder

Cited by 15 publications

References 20 publications

Episodic Memories: How do the Hippocampus and the Entorhinal Ring Attractors Cooperate to Create Them?

Episodic Memories: How do the Hippocampus and the Entorhinal Ring Attractors Cooperate to Create Them?

Hippocampus maintains a flexible and coherent map under reward flavor-landmark cue conflict

Episodic memories: how do the hippocampus and the entorhinal ring attractors cooperate to create them?

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