Effects of prefrontal lesions on avoidance and escape reflexes.

Retention of the avoidance and escape reflexes after removal of proreal and orbital gyri has been studied in adult cats. The ability to perform short-latency avoidance responses was severely impaired after prefrontal lesions, whereas no effect was found either on avoidance responses executed with longer latencies or on escape responses. Severity of impairment of the avoidance reflex was related to the pre-operative level of performance of the short-latency avoidance responses, which depend on the CS intensity, duration of the CS-US interval, and the type of inhibitory training. The post-operative retraining of the avoidance reflex performance was exclusively due to the increase in the proportion of avoidance responses executed with longer latencies. On the basis of neurophysiological and behavioral data it is postulated that different physiological mechanisms are responsible for execution of short-latency avoidance responses and avoidance responses with longer latencies. Only the first mechanism is destroyed after prefrontal lesions in cats.