Contrasting the Amnesic Effects of Temporary Inactivation with Lesions of the Hippocampus on Context Memory
Bibliographic record
Abstract
Lesions and temporary inactivation of the hippocampus (HPC) in rodents occasionally lead to discrepant amnesic effects. We directly compared and contrasted the retrograde amnesic effects that small HPC lesions (~50% damage), large HPC lesions (~80% damage), and combined dorsal and ventral HPC inactivation using the sodium channel blocker tetrodotoxin (TTX) had on contextual fear conditioning. Compared to control rats, large HPC lesions significantly reduced freezing during retention testing, a behaviour consistent with retrograde amnesia. In contrast, neither the small lesions nor the TTX inactivation significantly reduced freezing. The extent of damage was significantly and negatively correlated with retention performance (r(9) = -0.896, p < 0.001), suggesting that 70% or more of the HPC needed to be damaged to observe deficits. Importantly, TTX inactivation disrupted spatial memory in the Morris Water Task, confirming that our inactivation procedure did impair one form of HPC-dependent memory. To assess the extent of the TTX inactivation, immediate early gene expression was quantified in the HPC following the Morris Water Task. However, despite the behavioural impairment, we did not find a significant reduction in expression. We conclude that temporary inactivation of the HPC may fail to impair context fear memory because this technique does not sufficiently disrupt the HPC.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| 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".