Acquisition of the escape reflex in cats after the nucleus centralis of the amygdala lesions.

Three groups of 6 cats were trained in bar-press escape responses from unsignalled shock. Lesions of dorsolateral part of the amygdaloid nucleus centralis were made ,either 10 days or 35 days before training in two groups of subjects. The remaining 6 cats served as intact control ,group. The lesions resulted in a lengthening of instrumental response latencies especially in the final period of training. This was not caused by any changes in animals sensitivity and reactivity to painful stimulation since no differences between control and lesioned groups were observed at earlier stages of training. Further, no group effects were observed in threshold reactivity to shock. However, in contrast to the control cats, both lesioned groups performed escape responses to low intensity stimuli with very long latencies.