Hormonal and genetic regulation of song system differentiation in the zebra finch

Sex differences in brain and behavior exist across vertebrate species, but few are as dramatic as in the zebra finch. Adult males sing to court females and defend nest sites, a behavior they learn from their fathers. Normal females not sing at all. Parallel to these behavioral differences, the neural circuit controlling song is substantially more developed in males. Forebrain regions involved in the learning and production of song are larger in volume and contain more and larger cells in males. Our work investigates the molecular and hormonal mechanisms which permanently organize the development of brain and behavior, focusing on sex chromosome genes and steroids such as androgens and estrogens. Supported by NIH MH55488.