Long-term potentiation in the reciprocal corticohippocampal and corticocortical pathways in the chronically implanted, freely moving rat
Bibliographic record
Abstract
The hippocampus and adjacent cortical structures, including the entorhinal, perirhinal, and parahippocampal cortices, appear to serve as an integrated memory system. This extended hippocampal system is believed to influence memory and consolidation through an extensive set of reciprocal connections with widespread areas of the neocortex. Long-term potentiation (LTP) has been well-examined in the intrinsic connections of the hippocampus and neocortex. However, LTP in the pathways and structures thought to convey information between the hippocampus and neocortex has received little attention. If these pathways and structures are involved in information storage, and if LTP reflects a general synaptic encoding mechanism, then these systems are also likely to support LTP. In this paper we discuss a series of experiments aimed at investigating LTP in the efferents between the hippocampus and neocortex in chronically implanted animals. In the first experiment, the efferents of the perirhinal cortex were stimulated. LTP in the dentate gyrus (DG) reached asymptote more slowly than is typically seen following perforant path stimulation, whereas the frontal area (M1) reached asymptote more quickly than reported following corticocortical stimulation. The DG and M1 LTP was long-lasting, but entorhinal cortex LTP had decayed to baseline levels after a week. In the second experiment, the hippocampal efferents were stimulated. The perirhinal, entorhinal, and frontal cortex showed a similar slow potentiation, with only the perirhinal cortex levels returning to baseline after a week. In the third experiment, the projections from M1 were tested. The perirhinal cortex and hippocampus showed a long-lasting LTP. Although LTP was found in all pathways examined, there were differences in the induction and decay rate, and these properties may correspond to differences in learning rate and longevity of information storage.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 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 | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".