Rhythmic Constraints on Hippocampal Processing: State and Phase-Related Fluctuations of Synaptic Excitability During Theta and the Slow Oscillation
Bibliographic record
Abstract
Coordinated patterns of state-dependent synchronized oscillatory activity have been suggested to play differential roles in both the encoding and consolidation phases of hippocampal-dependent memories. Previous studies have concentrated on the mutually exclusive patterns of theta and sharp-wave/ripple activity because these were thought to be the only collective oscillatory patterns expressed in the hippocampus. Recently we (and others) have described a novel rhythmic activity expressed during anesthesia and deep sleep, the hippocampal slow oscillation (SO). In an attempt to describe the differential effects of theta and the SO on processing in the hippocampal circuit, we performed evoked potential analysis of two major pathways (the commissural and perforant) in urethan-anesthetized rats across spontaneously expressed theta and SO states. We show that synaptic excitability was significantly enhanced in all pathways during the SO as compared with theta with the exception of the medial perforant path to the dentate gyrus, which showed greater excitability during theta. Furthermore, within each ongoing rhythm, there was a phase-dependent modulation of synaptic excitability. This occurred across all sites and similarly favored the falling phase (positive to negative) of both theta and the SO. Differential effects on the input, processing, and output circuitries of the hippocampus across mutually exclusive coordinated oscillatory patterns expressed during different states may be relevant for the staging of memory processes in the medial temporal lobe.
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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 | 0.000 |
| 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 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".