Distinguished University Professor
UMD Biology 4227 Biology-Psychology Bldg.
When sound reaches one ear before the other, the brain uses the resulting interaural time differences (ITDs) to localize the sound. The barn owl is a nocturnal hunter and a good model for how we localize sound and process temporal information in general. We have shown that ITDs are translated into location in space in the brainstem. 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 ITD in nucleus laminaris. 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. Current research is focused on models of delay line-coincidence detector circuit, on the assembly of the map of sound localization during development and on how such circuits evolve. All projects develop from initial behavioral observations into systems, cellular and molecular levels of analysis.Animals :Birds, Reptiles Campus Institute : Lab :
UMD Hearing and Speech 0119 LeFrak Hall
The aging auditory system is characterized by anatomical alterations in peripheral and central structures. Aging is also accompanied by decline in cognitive processes. While many deficits in perception are attributed to peripheral hearing loss, there remain age-related alterations in processing of signals beyond those that are associated with sensitivity loss. The focus of this laboratory is investigation of the consequences of aging and hearing loss on auditory performance. Our work has shown that age-related deficits, independent of hearing loss, are primarily observed on measures of auditory temporal processing. The strategies employed include evaluation of behavioral performance on speech perception and psychoacoustic tasks, as well as electrophysiologic indices that alter stimulus timing or presentation rate.Animals : Campus Institute : Lab :