Representational similarity supports rapid context retrieval during fear discrimination in ventral hippocampus
Bibliographic record
Abstract
Summary The dorsal and ventral regions of the hippocampus (dCA1 and vCA1) are critical for contextual fear conditioning tasks, yet the dynamics of hippocampal neuronal representations during memory acquisition, retrieval, and extinction processes have yet to be fully elucidated. The canonical theory is that the hippocampus generates and retrieves spatial maps of contexts during memory acquisition and retrieval. It is hypothesized the hippocampus prevents memory interference by generating context representations that are dissimilar and the prediction follows that representation dissimilarity facilitates discrimination between contexts. Here, we developed a context fear memory retrieval task and combined it with 1-photon neuronal imaging in dCA1 and vCA1 of freely behaving mice to test this prediction. We identified several phenomena specific to vCA1. First, fear conditioning induced an immediate and strong representational change that was predictive of freezing behavior. During context discrimination, vCA1 representations of the threatening and neutral contexts became more similar. Third, during threatening context memory retrieval, vCA1 expressed rapid and strong context representations. These unexpected results suggest that representational similarity in vCA1 facilitates faster and more efficient network state transitions. In further support of this view, both phenomena of representational similarity and rapid context recall were no longer observed in vCA1 once fear behavior was extinguished. Together, these results reveal that vCA1 unexpectedly generates similar population codes, promoting faster transitions between network states essential for contextual fear memory retrieval. Highlights We established a novel context teleportation task that allows population level hippocampal recordings during key moments of threat memory acquisition, retrieval, and extinction. The ventral region of CA1 (vCA1) exhibited the greatest change in neural representation during fear memory acquisition, compared to dorsal CA1 (dCA1). After fear conditioning, representations for threatening and neutral contexts were more similar in vCA1 compared to dCA1, yet representational similarity in vCA1 supported rapid context memory retrieval. Context fear memory extinction reversed the context representation in vCA1 to patterns observed prior to fear conditioning. Graphical Abstract
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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 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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".