These data are the first to implicate a visual nucleus in the use of song. The data also complement previous finding with cowbirds suggesting that song learning involves visual attention to females. Taken as a whole, these results suggest that use of song depends on integration of auditory, vocal and visual information. In that female songbirds in many species assess multimodal performance of song, these findings with cowbirds suggest that future studies of brain and behaviour include a broader view of possible behavioural and neural correlates. The Association for the Study of Animal Behaviour K.A. Burke, M. Kuwajima, and D.R. Sengelaub.
Aromatase inhibition reduces dendritic growth in a sexually dimorphic rat spinal nucleus.
In normal males, SNB dendrites grow exuberantly through the first 4 weeks postnatally. Treatment with either of the T metabolites, dihydrotestosterone or estrogen, supports dendritic growth in castrates, but not to the lengths characteristic of intact males or T-treated castrates. In this study, we tested the hypohtesis that aromatization of androgens to estrogens was involved in the masculine development of SNB dendrites. Neither SNB somata size nor target muscle weight differed across groups. These results suggest that aromatization of androgens to estrogens is necessary for development of masculine SNB dendritic morphology.