Multiple-unit activity of the rabbit cerebral cortex during stimulus generalization of avoidance behavior

Abstract

Multiple-unit neuronal activity was recorded from three “nonspecific” polysensory regions of the cerebral cortex of rabbit during a test for stimulus generalization of an avoidance CR. Behavioral and cortical data obtained during the acquisition of the CR were reported in a previous paper. These data showed acquisition and maintenance of cortical multiple-unit responses in two of the three cortical areas, paralleling acquisition and maintenance of the CR. The present results show significant behavioral gradients of stimulus generalization to manipulation of frequency of the tonal CS used in conditioning. In addition, significant generalization gradients based upon cortical multiple-unit responses to the CS and test stimuli were obtained from one of the two cortical areas showing an acquisition effect. The peaks of behavioral and cortical gradients were invariably associated with the CS frequency in different groups of rabbits trained with different CS frequencies. Thus, a “prewiring” interpretation of the tonal effects was ruled out. Our data indicate that the two characteristics of acquired stimulus control (acquisition and stimulus specificity) commonly observed for behavioral conditioned responses can be demonstrated using neuronal responses of the CNS. Further, such effects appear to occur within limited regions of the brain.