Binaural interaction in the superior olivary complex of the cat: an analysis of field potentials evoked by binaural-beat stimuli.

THE ACCESSORY, or medial nucleus of the superior olivary complex is the first nucleus in the classical ascending auditory pathway that receives bilateral input. Both the anatomical structure and electrophysiological responses of the accessory nucleus suggest that it is a locus of binaural signal processing. The cells of the accessory nucleus have been shown to be responsive to interaural time and intensity disparities of binaurally presented clicks (5, 6) and to the interaural phase relations of binaurally presented tones (11). The field potentials of the accessory nucleus evoked by click and pure-tone stimuli have been correlated with the anatomical distribution of synaptic input from the two ears (3, 5, 17). Evidence of binaural interaction in the slowwave responses of the superior olivary complex to binaurally presented clicks was found by Rosenzweig and Amon (13). In the present study the field potentials of the superior olivary complex evoked by binaurally presented pure tones were analyzed to define further the mechanisms of binaural interaction