The behavior of chronic cats with lesions in the frontal association cortex

Cats with lesions in the proreal and anterior sigmoid gyri and substantial but subtotal degeneration in the mediodorsal thalamic nucleus were studied for 6 years post-operatively. The control group consisted of normal cats matched for age and previous experience. The results reported here and in Warren's previous progress report indicate that frontal cortical lesions result in several behavioral changes in cats which are like those seen in rhesus monkeys after frontal ablations: impairments in discrimination reversal, double alternation and active avoidance learning, retardation in the rate of habituation to novel neutral stimuli, and a decrease in aggression in competitive social situations. Cats with larger frontal lesions made more errors in reversal learning than cats with smaller lesions. Frontal cats, unlike frontal rhesus monkeys, are not hyperactive post-operatively and retain some capacity for learning delayed response in the WGTA. It is impossible at present to tell whether these discrepancies reflect species differences in the organization of the frontal lobe system or whether the frontal cortex spared in this series of cats is sufficient to mediate delayed response and to prevent the occurrence of hyperactivity.