Non-linear interaction of binaural stimuli

Nonlinear interaction in the acoustic brainstem response can be demonstrated by subtracting the response to binaural stimulation from the sum of responses to monaural stimulation. The resulting binaural difference waveform is nonflat during peaks IV and/or V of the acoustic brainstem response. The nonlinearity probably arises at some neural elements which lie in the ascending auditory brainstem and which receive inputs from both ears. The growth of the binaural difference was tested in rats under an increasing-stimulus-level series and the results were compared with the responses of two hypothetical models that can account for the binaural difference generation. The data are in good agreement with one of the models, which assumes that binaural difference is generated from contralateral inhibition under binaural stimulation