Posttraining lesions of the medial prefrontal cortex impair performance ofPavlovian 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 au tonomic adjustments but is not involved in classically conditioned somatomo tor responses unless the training conditions include reversal or trace cond itioning. The studies showing these effects have all used pretraining lesio ns. The present study assessed the effects of posttraining lesions on eyebl ink (EB) and heart rate (HR) conditioned responses (CRs) in both delay and trace conditioning paradigms in the rabbit (Oryctolagus cuniculus). Posttra ining lesions lowered the percentage of EB CRs during retesting compared wi th 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 tha t a critical mechanism in the mPFC is involved in retrieval of information during EB conditioning but that the mPFC integration of autonomic and somat omotor processes is not critical to this retrieval process.