UR Faculty: Joseph P. Walton

Ph.D. (1984) University of Florida	Joseph P. Walton Associate Professor of Surgery, Otolaryngology Division and Neurobiology and Anatomy, Director of Research In Audiology Primary Appointment: Surgery
Research: Neural Coding of Complex Sounds in the Aged Brain
Contact Information: E-Mail: joseph_walton@urmc.rochester.edu
University of Rochester School of Medicine and Dentistry 601 Elmwood Ave, Box 627 Rochester, New York 14642	Medical Center 1-5100 Phone: (585) 275-2501

Research Overview

One of the most prevalent health related complaints of the elderly is difficulty understanding speech in adverse listening conditions. The most severe problems occur in high levels of background noise, or with competing sound sources in different locations. Two physiological deficits are responsible. One is a loss in sensory receptors in the inner ear which results in a mild hearing loss while the second is due to presumed deficits in neural processing within the central auditory system. The neurophysiology and neuropharmacology underlying age-related deterioration in temporal processing of complex acoustics features is the principal research focus in my laboratory. A secondary interest is the study of the neural mechanisms which can extract relevant signals separated in auditory space from noise maskers, e.g. the cocktail party effect. Initial studies are devoted to the inferior colliculus, a key midbrain nucleus which integrates neural information from a multitude of lower brainstem centers. Two experimental approaches are used to asses neural encoding of complex signals; 1)we compare temporal processing of static (gap detection) and dynamic (amplitude modulation) changes in sound intensity in young and old cells using single-neuron recording techniques, and 2) using multibarrel electrodes we apply neurotransmitter antagonists and agonists on a nueron, and simultaneously record the effect this has on it's temporal processing ability. Our long-term goal in these studies is to unravel those changes which are responsible for the auditory perceptual deficits associated with the peripheral and central aging in the auditory system.

Recent Publications

Wilson, W.W, and Walton, J.P. Background noise improves gap detection in tonically inhibited inferior colliculus neurons. J. Neurophysiology (In press).

Barsz, K., Ison, J., Snell K. and Walton, J.P. Behavioral and neural measures of auditory temporal acuity in aging humans and mice. Neurobiology of Aging (In Press).

Frisina, R.D. and Walton, J.P. 2001, Neuroanatomy of the Mouse Central Auditory System. In: Handbook of Mouse Auditory Research: From Behavior to Molecular Biology, ed. J. Willott, CRC Press, Chapter 18.

Ison, J. R., Walton, J. P., Frisina, R. D., & O'Neill, W. E. 2001, Elicitation and inhibition of the startle reflex by acoustic transients: Studies of age-related changes in temporal processing. In: Handbook of Mouse Auditory research: From Behavior to Molecular Biology, ed J. F. Willott, CRC Press, Chapter 25.

Walton, J.P. and Burkard, R. Neurophysiological manifestations of aging in the peripheral and central auditory nervous system. In: Functional Neurobiology of Aging, eds. P.R. Hof and C.V. Mobbs, Academic Press, 581-599.

Frisina, D.R., Frisina, R.D., Snell K.B., Burkard, R., Walton, J.P. and Ison, J.R. Auditory temporal processing during aging central auditory nervous system. In: Functional Neurobiology of Aging, eds. P.R. Hof and C.V. Mobbs, Academic Press, 565-581.

Barsz, K., Wilson , W.W. and Walton, J.P. 2000, Background noise differentially effects temporal coding by tonic units in the mouse inferior colliculus. Hearing Research, 150:149-160.

Frisina, R.D. & Walton, J.P. Aging of the mouse central auditory system. In: Handbook of Mouse Auditory Research: From Behavior to Molecular Biology, ed. James P.Willott, CRC Press, NY (In press).

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