When sound reaches one ear before the other, the brain uses the resulting interaural time differences to localize the sound. We have studied how the brain localizes sound in the barn owl, a highly skilled nocturnal hunter. Barn owls are also good models for how we ourselves localize sound and process temporal information. In the brain, interaural time differences are translated into location in space. Detection of these time differences depends upon two mechanisms of general significance to neurobiology, delay lines and coincidence detection. Incoming axons form delay lines to create maps of time difference in the brain. Their postsynaptic targets act as coincidence detectors and fire maximally when the interaural time difference is equal but opposite to the delay imposed by the afferent axons. In recent years at the MBL we have compared sound localization circuits in crocodilians, birds and mammals and found many shared computational strategies.

Catherine Carr is Professor of Biology at the University of Maryland, College Park. She earned her B.S. in Zoology from the University of Cape Town in 1977, her M.A. in Biology from State University New York at Buffalo in 1978, her Ph. D. in Neuroscience from University of California at San Diego in 1984, and completed a postdoctoral fellowship at California Institute of Technology in 1987. In 1984, Dr. Carr received a National Research Service Award and was awarded the Society for Neurotheology Prize for an Outstanding Paper by a Young Investigator. She was an Alfred P. Sloan Research Fellow in 1988. From 1992 to 1998, Dr. Carr was a member of the NIH Hearing Panel and became a member again in 2002. She was an Assistant Professor of Zoology at the University of Maryland, College Park from 1990 to 1995, an Associate Professor from 1995 to 1999, and became Professor of Biology in 1999. In 1998, she received the University of Maryland Life Sciences Excellence in Research Award. Since 2001, she has been Director of the Howard Hughes Undergraduate Teaching Program at the University of Maryland. Dr. Carr's career at the MBL began as a Scholar-In-Residence for the Neural Systems and Behavior course in 1990. She was appointed to the faculty of the course in 1995 and has been Co-Director since 2000.

Daniel Johnston will introduce Dr. Carr. Dr. Johnston earned his B.S. in Electrical Engineering from the University of Virginia, Charlottesville in 1970, his Ph. D. in Biomedical Engineering and Physiology from Duke University in 1974, and his Postdoctoral Training in Cellular Neurophysiology of Epilepsy from University of Minnesota, Minneapolis from 1973 to 1975. He has been a Professor in the Department of Neurology and Molecular Physiology and Biophysics at Baylor College of Medicine since 1986, and a Professor of Neuroscience at the college since 1989. Since 1975 he has served as a reviewer for scientific journals including Science and Nature. In 2001, Dr. Johnston received the Barbara and Corbin J. Robertson, Jr. Presidential Award for Excellence in Education from Baylor College of Medicine. He is an MBL Corporation Member, a 2004 Dart Foundation Scholar in Learning and Memory, a member of the Whitman Building Committee, and a member of the Steering Committee for the Neuroscience Institute.