Effects of ipsilateral rostral pontine reticular lesions on retention of classically conditioned nictitating membrane and eyelid responses

Abstract

Neural unit recordings from the pontine reticular formation in well-trained rabbits show a tone-evoked onset response (CS), a suggestion of an airpuff onset response (UCS), and an increase in unit activity that is similar to the topography of the learned response. When this same area is destroyed by unilateral electrolytic lesions (in another group of animals), retention of the learned response is abolished but the reflex response is essentially unchanged. Since a recent study (McCormick, Lavond, Clark, Kettner, Rising, & Thompson, 1981) has shown that unilateral cerebellar lesions also produce a complete and selective abolition of the CR, and the CR cannot be reinstated with retraining, these findings are discussed in terms of a common circuitry that encodes the engram for short-delay classical conditioning of striated muscle responses.