Effects of Insular Cortex Lesions on Conditioned Taste Aversion and Latent Inhibition in the Rat

The present study tested the hypothesis that lesions of the insular cortex of the rat retard the acquisition of conditioned taste aversions (CTAs) because of an impairment in the detection of the novelty of taste stimuli. Demonstrating the expected latent inhibition effect, nonlesioned control subjects acquired CTAs more rapidly when the conditioned stimulus (0.15% sodium saccharin) was novel rather than familiar (achieved by pre-exposure to the to-be-conditioned taste cue). However, rats with insular cortex lesions acquired taste aversions at the same slow rate regardless of whether the saccharin was novel or familiar. The pattern of behavioural deficits obtained cannot be interpreted as disruptions of taste detection or stimulus intensity, but is consistent with the view that insular cortex lesions disrupt taste neophobia, a dysfunction that consequently retards CTA acquisition because of a latent inhibition-like effect.