Evoked potentials in the reticular formation during auditory conditioning of the corneal reflex in the chronic decerebrate rat

Abstract

The chronic decerebrate rat preparation was used to study electrical activity in the reticular formation during development of the classically conditioned eyeblink reflex to a tone. With persistent training a conditioned blink reflex was established in 8 out of 11 rats. A control group of four rats received unpaired presentations of the conditioned and unconditioned stimuli and served as a control. Evoked potentials in response to the auditory conditioned stimulus were recorded in medullary and pontine reticular nuclei during conditioning. The amplitude of the main negative wave of the response showed a significant increase during the establishment of a conditioned response but the amplitude of potentials recorded from the medullary reticular formation showed no significant change. There was no change in the amplitude of potentials recorded in either the pontine or medullary reticular nuclei in the control "pseudoconditioning" group or in the three rats which underwent training but did not develop a conditioned response. It is concluded that structures within the pontine reticular formation play an active part in the acquisition phase of the conditioned blink reflex in the chronic decerebrate rat.