Cortical Reactivation of Non-Spatial and Spatial Memory Representations Coordinate with Hippocampus to Form a Memory Dialogue
Bibliographic record
Abstract
Abstract Episodic memory depends on the association of diverse attribute representations that are distributed across the neocortex, and evidence suggests that these attributes are linked, at least initially, by the hippocampus, which orchestrates retrieval and the offline replay of experience during memory consolidation. The dynamics that characterize this hippocampal-cortical dialogue, however, are only partly understood. Although it was originally proposed that replay is initiated in CA3, with the spontaneous emission of sharp-wave ripple (SWR) bursts, increasing evidence suggests that cortex may seed the process with partial information, leading to pattern completion in CA3 and subsequent global reactivation of the episode. A recent study has shown that the secondary motor cortex (M2), among other areas, carries two distinct types of representations: place cell-like activity, which relies on an intact hippocampus for its development, and responses tied to visuo-tactile cues — the ‘attributes’ of the experience, which do not require the hippocampus. Using two-photon Ca 2+ imaging, while simultaneously acquiring LFP from the ipsilateral CA1, we assessed the interactions among cortical retrieval of visuo-tactile attributes of previous experiences in a virtual environment, hippocampal SWR, and the cortical reinstatement of the spatial aspects of the same experiences. During rest after the experience, two types of reactivation events occurred, which separately conveyed information about spatial trajectories and visuo-tactile attributes. Reactivation of attribute information preceded that of trajectories in relation to hippocampal SWRs. Furthermore, paired reactivations of cue and trajectory information supported similar features of previous experiences. These results are consistent with the hypothesis that cortical retrieval of non-spatial attributes of recent experience seeds hippocampal reactivation of associated spatial sequences, which is followed by retrieval of episodic memory traces.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".