Orienting and classical conditioning in the rabbit (Oryctolagus cuniculus): effects of septal area lesions.

Rabbits with either sham or septal lesions recieved differential classical conditioning training in which tones of different frequencies served as CSs and paraorbital shock served as the UCS. Eyeblink (EB), EMG, and heart rate (HR) CRs were concommitantly assessed. Free field activity was also studied in selected animals. Animals with septal lesions revealed an impaired EB discrimination which resulted from increased responding to the CS-. These animals showed HR CRs of greater magnitude than sham animals. The HR discrimination was, however, unimpaired by septal lesions. Differential EMG activity also occurred, but was unaffected by septal destruction. Septal lesions resulted in greater free-field activity associated with visual stimulation, but no differences were obtained between septal and sham animals in the dark. It is suggested that these results were due to an enhanced reactivity to environmental stimulation, possibly related to dysfunctions of the orienting reflex.