The effect of lesions of the insular cortex on instrumental conditioning: Evidence for a role in incentive memory

In three experiments, we assessed the effect of lesions aimed at the gustat ory region of the insular cortex on instrumental conditioning in rats. In e xperiment 1, the lesion had no effect on the acquisition of either lever pr essing or chain pulling in food-deprived rats whether these actions earned food pellets or a maltodextrin solution. The lesion did, however, attenuate the impact of outcome devaluation, induced by sensory-specific satiety, on instrumental performance but only when assessed in an extinction test. Thi s effect was not secondary to an impairment in instrumental learning; in ex periment 2, no evidence was found to suggest that the lesioned rats differe d from shams in their ability to encode the specific action-outcome conting encies to which they were exposed during training. In experiment 3, however , lesioned rats were found to be insensitive to the impact of an incentive learning treatment conducted when they were undeprived; although, again, th is deficit was confined to a test conducted in extinction. These results ar e consistent with the view that, in instrumental conditioning, the gustator y region of the insular cortex is involved in encoding the taste of food ou tcomes in memory and, hence, in encoding the incentive value assigned to th ese outcomes on the basis of prevailing motivational conditions.