Testis-dependent and -independent effects of photoperiod on volumes of song control nuclei in American tree sparrows (Spizella arborea).

@article{Bernard1997TestisdependentA,
  title={Testis-dependent and -independent effects of photoperiod on volumes of song control nuclei in American tree sparrows (Spizella arborea).},
  author={Daniel J Bernard and Fred E. Wilson and Gregory F Ball},
  journal={Brain research},
  year={1997},
  volume={760 1-2},
  pages={163-9}
}
Songbirds exhibit seasonal changes in the volumes of song control nuclei. Birds on long, spring-like days have larger nuclei than do birds on short, winter-like days. The mechanisms mediating volumetric changes have not been determined unequivocally, but testosterone (T) is probably involved. This study examined whether testicular factors are uniquely responsible for seasonal changes in the song system, or whether photoperiod has testis-independent effects. Male American tree sparrows were… CONTINUE READING