Effects of caudate nuclei or frontal cortical ablations in kittens: Motor activity and visual discrimination performance in neonatal and juvenile kittens

Abstract

Motor activity and visual discrimination performance were assessed in kittens that had received either bilateral ablations of the caudate nuclei (acaudate) or frontal cortices (afrontal) during the first month of life. Kittens (tested between 36 and 60 days of age) with large bilateral caudate ablations were hyperactive compared to their intact littermates and a group of sham-operated kittens that underwent the same surgical procedures as the acaudates except for the caudate ablation. The afrontals were slightly more active than intact kittens but not as active as acaudates. Visual discrimination performance was assessed when the kittens were about 3 months old. Minimal group differences in performance occurred during acquisition of the discrimination. During reversal of the original discrimination the kittens with large caudate lesions continued responding to the previously reinforced cue significantly longer than animals in any other group. Those with frontal lesions did not perseverate in this manner but displayed highly variable performance on most aspects of the tasks. These results are consistent with the idea that a major consequence of caudate damage is a loss of flexibility in adopting new responses when the previously reinforced behavior is no longer appropriate. The results also indicate that some of the behavioral effects of neonatal and adult caudate and cortical lesions are qualitatively similar.