ASA 125th Meeting Ottawa 1993 May

2aPP6. Nonlinearity of spectra processing in the dorsal cochlear nucleus (DCN).

Eric D. Young

Israel Nelken

Johns Hopkins Univ., 720 Rutland Ave., Baltimore, MD 21205

George A. Spirou

West Virginia Univ., Morgantown, WV 26506

Most studies of the neural representation of complex stimuli assume a parallel filterband form of representation in which neural response is plotted against position on the basilar membrane (or best frequency, BF). Such a representation assumes that the neural response reflects the energy in the signal within the neuron's tuning curve and makes most sense if neural tuning properties are linear or only weakly nonlinear. By contrast, the principal cells of the DCN integrate energy across their response areas in a highly nonlinear fashion. These neurons give predominantly inhibitory responses to narrow-band stimuli and excitatory responses to broadband stimuli. Their responses to broadband stimuli cannot be predicted by a filtering model, in which the response equals the sum of narrow-band responses, weighted by the stimulus spectrum. Similarly, a narrow notch in a noise band centered on a unit's BF also gives an inhibitory response. This inhibitory response also cannot be predicted from narrow-band responses and may represent a specialization for detecting spectral notches produced by the directional filtering properties of the external ear. [Work supported by NIH, Keck Foundation, and Fulbright Foundation.]

All posters will be on display from 9:00 a.m. to 12:00 noon. To allow contributors an opportunity to see other posters, contributors of odd-numbered papers will be at their posters from 9:00 to 10:30 a.m. and contributors of even-numbered papers will be at their posters from 10:30 a.m. to 12:00 noon.