Representation of binaural stimuli by single units in primary auditory cortex of unanesthetized cats.

Abstract

The stimulus-evoked activity of single units in the left primary auditory cortex (AI) of cats immobilized with gallamine triethiodide was observed as tone bursts, noise bursts, or clicks were presented at a moderate intensity to the right ear, to the left ear, and simultaneously to both ears. The right ear is represented more strongly in that more cells respond to monaural stimulation of the right ear than the left ear. An ear is said to be “represented” if a unit responds to stimulation of that ear, or if the response to stimulation of the other ear is modified by stimulation of that ear. There is extensive overlap of the populations of units representing the two ears; the population representing the left ear is almost completely contained within the larger population representing the right ear. The majority of units exhibited some form of binaural interaction. Binaural summation was the most common form of interaction; other units exhibited binaural inhibition or combinations of summation and inhibition.