Changes in the functional connectome and behavior after exposure to chronic stress and increasing neurogenesis
Bibliographic record
Abstract
Abstract Addition of new neurons to the dentate gyrus might change the activity of neural circuitry in the areas which the hippocampus projects to. The size of the hippocampus and the number of adult newborn granule cells are decreased by unpredictable chronic mild stress (UCMS). Additionally, one of the notable effects of chronic stress is the induction of ΔFosB, an unusually stable transcription factor which accumulates over time in several brain areas. This accumulation has been observed in many animal models of depression and it could have a protective role against stress, but no studies so far have explored how a specific increase in neurogenesis might regulate the induction and which brain networks might be predominately affected. We attempted to investigate the role of increasing adult hippocampal neurogenesis on stress-related behavior and the functional brain circuitry involved in mice exposed to UCMS. We used iBax mice, in which the pro-apoptotic gene Bax can be selectively ablated in neural stem cells, therefore inducibly enhancing survival of newborn neurons after tamoxifen administration. The animals were exposed to UCMS for 9 weeks and treated with tamoxifen in week 3 after the beginning of UCMS. In week 8, they were submitted to a battery of behavioral tests to assess depressive-like and anxiety-like behavior. In week 9, blood was collected to assess basal corticosterone levels, and the animals were sacrificed and their brain collected for ΔFosB immunohistochemistry. Brain-wide maps of ΔFosB expression were constructed and graph theoretical analyses were used to study the changes in brain networks after stress. UCMS induced negative correlations between the lateral entorhinal cortex and both the hippocampal structures and the nucleus accumbens in the VEH-treated mice, which were not present in other groups. Ranking nodes by degree reveals a strong thalamic-cortical signature in both non-stress (NS) groups. Exposure to UCMS seems to induce activity in thalamic areas and cerebral nuclei, with a different signature in the UCMS TAM group, which seems to completely “disengage” the neocortex and has most of its nodes with the most connections in the thalamic areas.
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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) | 0.001 | 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".