Rapid increases in immature synapses parallel estrogen-induced hippocampal learning enhancements
Bibliographic record
Abstract
Dramatic increases in hippocampal spine synapse density are known to occur within minutes of estrogen exposure. Until now, it has been assumed that enhanced spinogenesis increased excitatory input received by the CA1 pyramidal neurons, but how this facilitated learning and memory was unclear. Delivery of 17β-estradiol or an estrogen receptor (ER)-α (but not ER-β) agonist into the dorsal hippocampus rapidly improved general discrimination learning in female mice. The same treatments increased CA1 dendritic spines in hippocampal sections over a time course consistent with the learning acquisition phase. Surprisingly, estrogen-activated spinogenesis was associated with a decrease in CA1 hippocampal excitatory input, rapidly and transiently reducing CA1 AMPA activity via a mechanism likely reflecting AMPA receptor internalization and creation of silent or immature synapses. We propose that estrogens promote hippocampally mediated learning via a mechanism resembling some of the broad features of normal development, an initial overproduction of functionally immature connections being subsequently "pruned" by experience.
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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 | 0.002 | 0.005 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.002 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 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 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".