The International Research Fellowship Program enables U.S. scientists and engineers to conduct nine to twenty-four months of research abroad. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad.
This award will support a twenty-four-month research fellowship by Dr. Thomas W. Small to work with Dr. Winfried Wojtenek, Universidad San Francisco de Quito in Quito, Ecuador, and with Dr. Ignacio Moore, Virginia Technological University, Blacksburg, Virginia. Support for this project comes from the Office of International Science and Engineering's (OISE) Americas Program.
The brain changes seasonally in form and function and controls seasonal behaviors. One of the best examples of this brain plasticity is the neural song control system and song behavior in songbirds. Traditional models of brain plasticity in birds have investigated temperate zone species where the crucial mediators are the seasonal changes in day length and sex steroids. This research project examines the role of steroid hormones, independent of day length, in regulating seasonal changes in brain structure and song behavior in the tropical rufous-collared sparrow (Zonotrichia capensis). The bird populations being investigated live on the equator, in Ecuador, and despite not experiencing seasonal changes in day length they breed seasonally and exhibit seasonal changes in the song control system. The studies being conducted are (1) a comparison of steroid hormone receptor density between the song control nuclei of non-breeding and breeding adult males, and (2) investigating the relative roles of testosterone and estrogen in mediating the seasonal changes in the song control system. These studies are being conducted using free-ranging birds and captive birds maintained under natural conditions. Because these experiments are being conducted under natural conditions, independent of day length effects on hormones, they are providing important insights into the regulation of behavior and brain plasticity by hormones. Additionally, these studies are providing crucial information on how animals interact with their environment.
