Sex differences in songbirds 25 years later: What have we learned and where do we go?
Bibliographic record
Abstract
About 25 years ago, Nottebohm and Arnold reported that there are profound male-biased sex differences in volume in selected nuclei in telencephalic portions of the song control system. This review focuses on issues related to the cellular bases of these sex differences in volume and comparative studies that might elucidate the function of this variation between the sexes. Studies utilizing a variety of neurohistological methods in several different species to define the boundaries of two key telencephalic song nuclei HVc and the robust nucleus of the archistriatum (RA) all tend to find a sex difference in volume in agreement with Nissl-defined boundaries. Sex differences in volume in nuclei such as HVc and RA are associated with differences in cell size and cell number. Other attributes of the phenotype of cells in these nuclei are also different in males and females such as the number of cells expressing androgen receptors. Comparative studies have been employed to understand the function of these sex differences in the brain. In some songbird species, females sing rarely or not at all, and the brain nuclei that control song are many times larger volume in males than females. In other species, males and females sing approximately equally, and the brain nuclei that control song are approximately equal between the sexes. Recently, statistical methods have been employed to control for phylogenetic effects while comparing the co-evolution of traits. This analysis indicates that the evolution of sex differences in song has co-evolved with the evolution of sex differences in singing behavior in songbird species. Future studies should focus on the function of the smaller song control nuclei of females and investigate the role these nuclei might play in perception as well as in production.
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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 | 0.003 | 0.005 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.002 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.004 |
| Scholarly communication | 0.002 | 0.004 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.002 | 0.005 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
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".