Dr. Joseph M. Casto
Office - FSA 227, Lab – 227 FSA. Phone: 8-7351, Email: jmcasto@ilstu.edu
Hormones, Brain, and Behavior: Research in Behavioral Neuroendocrinology
I investigate the influences of sex hormones such as testosterone and estradiol on brain and behavior in rodents and songbirds. Sex hormones can affect behavior by interacting with the nervous system both during early development as well as in adulthood. By experimentally manipulating exposure to androgens or estrogens at various points in an animal’s life I investigate how behavior, morphology, and physiology are integrated into adaptive phenotypes.
Prenatal androgens and the development of sex-typical behavior patterns in rats
Neonatal inhibition of androgen action can completely block masculinization and promote feminization of male-typical behaviors such as juvenile rough-and-tumble play and adult male mating behavior. This has led some to conclude that androgen action during prenatal development has little influence on the development of these behaviors. My previous research indicates that in utero androgen action is indeed important for the normal development of male-typical behavior patterns.
Hormonal control of sex differences in songbird brains
Unlike most other birds, songbirds learn the songs they sing from adults of their species. These birds have evolved specialized brain circuits, collectively know as the “song system,” that mediate the learning and production of song. In some species of songbirds females sing substantially less than males, while in others females are similar to males with respect to singing. Sex differences in the size and complexity of the song system tend to mirror sex differences in singing within species. I study the role of early exposure to steroid
Field neuroscience: Brain-behavior relationships in free-living animals
More recently, my research has included field-based studies. I have begun to investigate brain-behavior associations in free-living birds in order to determine if previous laboratory-based studies generalize to field settings. Along with my collaborators, I have studied the relationship between hippocampus volume and testosterone-induced increases in home range size, as well as the relationships between the volumes of various song control nuclei and testosterone-induced increases in singing in Dark-eyed juncos (Junco hyemalis). Our results suggest that some basic laboratory findings regarding brain-behavior correlations do not generalize to free-living birds.