Computer Simulation of Sharpening Effects on Response Areas of Single Auditory Units

This simulation deals with the problem of the neural mechanisms that may be responsible for the sharpening of response areas, in terms of sound frequency, that were observed in single neurons of the upper-auditory relay nuclei. It assumes that there is tonotopic localization and lateral inhibition in each nucleus. The model is a network that consists of elements with similar connections. The parameters of the model were varied until an appropriate sharpening was obtained. It became clear that a threshold parameter for individual elements was also necessary to create a sharpening similar to the sharpening seen in electrophysiological experiments. The presence of spontaneous activity served a little to emphasize the sharpening. The study also indicates that a negative feedback, i.e., recurrent inhibition, was necessary for obtaining reliable responses over a wide range of sound intensities. [Work supported in part by National Institutes of Health International Postdoctoral Fellowship, and in part by NIH grants and the Joint Services Electronics Program.]