Assistant Director, Research Ethics & Compliance
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Hormones, Brain, and Behavior: Research in Behavioral Neuroendocrinology
One area of investigation in the lab is the influence 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 we 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. Our previous research indicates that in utero androgen action is indeed important for the normal development of male-typical behavior patterns. (Collaborators: Byron Ward & Andrzej Bartke)
Hormonal control of sex differences in songbird brains. Unlike most other birds, songbirds learn the songs they sing from conspecific adults. These birds have evolved specialized brain circuits, collectively know as the “song system,” that mediate the learning and production of song. In some songbird species females sing substantially less than males, while in others males and females sing equally. Sex differences in the size and complexity of the song system tend to mirror sex differences in singing within species. I investigate the role of early exposure to steroid hormones in the development of sex differences in the song system in European starlings (Sturnus vulgaris), an introduced songbird species and agricultural pest common to the Midwest (Collaborator: Greg Ball).
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. (Collaborators:Tom Smulders, Tim DeVoogd & Ellen Ketterson)