ASA 125th Meeting Ottawa 1993 May

2aPP2. Modeling of precedence-effect behavior in single neurons and in human listeners.

H. Steven Colburn

Hany Ibrahim

Dept. of Biomed. Eng., Boston Univ., 44 Cummington St., Boston, MA 02215

Many of the physiological observations of Yin (reported in this session) are consistent with the precedence effect observed in human psychophysical data. In an attempt to understand the mechanisms involved in the generation of these observations, models for the observed neural interactions are being investigated. Since precedence-effect phenomena are fundamentally related to transient parts of stimuli, the models of these phenomena incorporate descriptions of responses to transient stimuli. In contrast to models for the observed binaural interaction in the medial superior olive (MSO) for sinusoidal stimuli, models for responses to click stimuli in the inferior colliculus (IC) must include inhibitory effects. These effects are long-lasting (tens of milliseconds) and asymmetric, consistent with earlier data from the IC with binaural clicks [L. H. Carney and T. C. T. Yin, J. Neurophys. 62, 144--161 (1989)]. The location of this inhibitory interaction is not clear since physiological measurements in lower levels of the brainstem (e.g., MSO) have not included the appropriate transient stimuli. The physiological responses from the IC will also be discussed in the context of recent psychophysical observations which suggest that the precedence effect may be a very central phenomenon. [Work supported by NIDCD.]