Emergence of spatial impairment in rats following specific cholinergic depletion of the medial septum combined with chronic stress
Bibliographic record
Abstract
A consistent finding in patients suffering from Alzheimer's disease is a loss of the cholinergic neurons of the basal forebrain that project to the hippocampus. However, the role this depletion plays in the development of Alzheimer's disease remains unclear. The loss of this ascending neurotransmitter system could potentially render hippocampal neurons more susceptible to further insult, such as chronic stress, ultimately resulting in neuronal death and memory loss. We explored this possibility by using the highly specific toxin 192 IgG-Saporin to destroy the majority of cholinergic activity in the septo-hippocampal pathway in rats. Following depletion, rats were subjected to 2 weeks of restraint stress. Rats were divided into two groups and were tested either on a hippocampal-dependent (water maze) task or a hippocampal-independent task (fear conditioning to tone and context). We showed that cholinergic depletion or stress alone had no effect on the successful performance of either of the tasks. However, rats with a combination of cholinergic depletion and stress were significantly impaired on the water-maze task. No deficits were apparent in the combined group that was tested on fear conditioning to tone or context, suggesting that this impairment is specific to spatial working memory. These rats had no obvious hippocampal neuronal loss or damage; however, there were likely subtle changes in hippocampal processing that led to the observed deficit on the hippocampal-dependent task. These findings support our theory that cholinergic depletion of the medial septum increases hippocampal vulnerability to further insults such as stress.
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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) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.002 | 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".