Neuronal substrate of classical conditioning in the hippocampus.

Neuronal activity in dorsal hippocampus was recorded in rabbits-during classical conditioning of nictitating membrane response, with tone as conditioned stimulus and corneal air puff as unconditioned stimulus. Unit activity in hippocampus rapidly forms a temporal neuronal "model" of the behavioral response early in training. This hippocampal response does not develop in control animals given unpaired stimuli.