Acoustic communication, including human speech, is mediated by sounds that vary in both time and frequency. Our research focuses on the neural mechanisms involved in the analysis of complex acoustic signals at various levels of the auditory system, from brainstem to cortex. Our primary research focuses on the encoding of frequency modulations, which are brief, time-varying tones characterizing consonant-vowel transitions in human speech, as well as the sounds used by nearly all mammals (including bats) in social communication. Neurons in the bat midbrain are often directionally selective, i.e., they only respond to either ascending or descending sweeps.  Recent experiments are aimed at understanding the mechanisms underlying directional selectivity by manipulating the frequency and timing of tone sequences to mimic the FM sweep.  We are studying these mechanisms in the "central acoustic tract", a “fast” pathway linking the auditory brainstem directly to both the midbrain and thalamus, which in turn project to the auditory cortex, prefrontal cortex, and the limbic system (amygdala). Techniques include digital sound synthesis, neurophysiological recording of single-unit activity, anatomical tract tracing, and immunocytochemistry.

A second area of investigation is aimed at understanding age-related auditory processing deficits. Aging studies are conducted by two separate NIA-funded projects. One is a collaborative Program Project involving laboratories at the University of Rochester and Rochester Institute of Technology. The goal of this project is to understand the age-related deterioration in temporal processing underlying deficits in speech perception in noisy environments in elderly people with little or no peripheral hearing loss. To that end, human and animal subjects (mice) are tested with common techniques at functionally comparable life stages, with the intention of ultimately ameliorating this problem.

A third collaborative project is with Dr. Gary Paige, chair of the Department of Neurobiology and Anatomy. In this study, we are investigating in human subjects how spatial information separately encoded in visual, auditory and vestibular coordinates is combined to create a unified sense of space, and how this concordance of spatial information processing changes with age.