Binaural-Discrimination Enhancement in Brainstem Neurons

Binaural interactions at the neural level of cat have been investigated for single elements within or near the medial superior olivary nucleus (MSO) of cat. A type of neuron has been studied in the area of the MSO to which at least one ear contributes both excitatory and inhibitory components. This type of cell responds to both LE-monaural and RE-monaural stimulation. At some binaural-phase conditions, the response of the cell exceeds the sum of the monaurally produced responses. However, at some other phase angles, spike production is less than that produced monaurally. These cells are similar to those found by Rose et al. in the inferior colliculus. The complex excitatory-inhibitory interaction, as implied by the binaural-response characteristics, provides a mechanism for enhancement of binaural time-difference discrimination and also demonstrates the type of cell required for correlation models of frequency discrimination. [Research supported in part by National Science Foundation.]