An ablation study of the auditory cortex in the cat using binaural tonal patterns.

Abstract

Eight cats were trained to respond in a double grill box to a change in a binaural pattern of tones produced by alternately stimulating one and then the opposite ear. Tests showed that the cats did not, in fact, listen to a binaural pattern but instead waited for a frequency change to occur in one ear. Ablation of auditory cortex contralateral to the side of the attentive ear resulted in an amnesia, while ablation of the auditory cortex ipsilateral to the attentive side had no effect upon the learned habit. However, the ipsilateral cortex can serve as the site of the engram as was shown by subsequent ablation of the intact side. Even after removal of both sides, cats can relearn the discrimination since habituation to the 2 ears can occur independently. How the engram is isolated to 1 hemisphere remains unanswered, but some clues to the answer are discussed.