Posttraining lesions of the medial prefrontal cortex impair performance of Pavlovian eyeblink conditioning but have no effect on concomitant heart rate changes in rabbits (Oryctolagus cuniculus).
The medial prefrontal cortex (mPFC) plays a critical role in conditioned autonomic adjustments but is not involved in classically conditioned somatomotor responses unless the training conditions include reversal or trace conditioning. The studies showing these effects have all used pretraining lesions. The present study assessed the effects of posttraining lesions on eyeblink (EB) and heart rate (HR) conditioned responses (CRs) in both delay and trace conditioning paradigms in the rabbit (Oryctolagus cuniculus). Posttraining lesions lowered the percentage of EB CRs during retesting compared with pretesting levels for both delay and trace conditioning. Control lesions and pretraining lesions produced no significant effects during retesting. Posttraining lesions had no effect on the HR CR. These findings suggest that a critical mechanism in the mPFC is involved in retrieval of information during EB conditioning but that the mPFC integration of autonomic and somatomotor processes is not critical to this retrieval process.