Topography of binaural interaction in the auditory brainstem response

The scalp topography of binaural interaction (BI) in the auditory brainstem response (ABR) was studied in fourteen normal individuals. BI was observed from all recording sites of the scalp, and the peak amplitude was noted mostly in the bilateral parietal and occipital regions. There was a significant difference in amplitude shown by significance probability mapping (SPM) when the waveform obtained by binaural stimulation was compared with the sum of the waves obtained by monaural stimulation. The topography of BI was different from that of the wave III and the wave IV/V complex. In contrast to previous reports by other workers, we found that BI mainly corresponded to the first half of the wave IV/V complex.