ASA 129th Meeting - Washington, DC - 1995 May 30 .. Jun 06

2pPP68. A comparison of the efficiency and accuracy of medial superior olive cell simulations.

Trevor M. Shackleton

Dept. of Exp. Psychol., Univ. of Sussex, Brighton, E. Sussex BN1 9QG, UK

Binaural processing of interaural time differences (ITDs) is widely believed to be performed by a cross-correlation mechanism. Cells have been found in the medial-superior olive (MSO) and inferior colliculus which respond most strongly when presented with stimuli with a characteristic ITD (EE cells). These cells are believed to form the basis for such a mechanism. In this study we compare the performance of cells based on simple cross-correlation, coincidence detector cells based on a novel deterministic method, and coincidence detectors based on Monte-Carlo simulation. The deterministic model is based upon the requirement that the probability of a given number of inputs from the auditory nerves of either ear must exceed a threshold amount within a finite time (coincidence window) before the modeled cell can fire. We examine the firing rate and vector strength as a function of ITD, overall level, and interaural level difference (ILD) and compare our results with the data from cells in the MSO. We find that a simple cross-correlation cell is inadequate to describe the data. However, the deterministic cell and Monte-Carlo simulation, both with a coincidence window width of 0.2 ms, describe the data very well. [Work supported by The Wellcome Trust, UK.]