Binaural interaction at the inferior colliculi.

Abstract

Electrophysiological responses were recorded at the midbrain level in cats before and after section of the commissure of the inferior colliculi with the stimulus source a click stimulus delivered independently to the two ears. Recording electrodes were in the inferior colliculi. Although responses in the ipsilateral and contralateral sides showed distinguishable differences in amplitude and wave form, evidence for binaural interaction came from the following findings: (1) "The response to simultaneous stimulation of the two ears is smaller in amplitude than the sum of the responses to monaural stimulation of each ear." (2) "When one ear is stimulated slightly before the other, the response to the second stimulus is modified." Severance of the commissure of the inferior colliculi did not abolish this binaural interaction.