HIPPOCAMPAL-LESIONS SLOW EXTINCTION OF A CONDITIONED TASTE-AVERSION IN RATS

Rats were subjected to either a bilateral removal of the superior cervical ganglia or to a sham operation of the neck. In subsequent operations, these animals underwent either bilateral dorsal hippocampal lesions, bilateral neopallial lesions or no further operation. Removal of the superior cervical ganglia prevented the anomalous innervation of the remaining hippocampal tissue. All animals then learned a conditioned taste aversion to a sweetened milk solution (CS) following LiCl-induced gastrointestinal illness (UCS). The rats with hippocampal lesions were significantly slower to extinguish the aversion conditioning across the 14 day recovery period than were controls. There was no effect of any manipulation on the acquisition of the conditioned taste aversion, and there were no behavioral consequences of the presence or absence of the anomalous innervation. The slower extinction of the taste aversion shown by the hippocampal lesioned rats was discussed in terms of a lessened impact of the pre-illness exposure to the CS in these animals. © 1979.