Behaviorally evoked hippocampal theta waves: a cholinergic response.

Forced running in a treadmill results in the instantaneous appearance of a synchronous electroencephalographic pattern in the dorsal hippocampus of the rat. A similar bioelectric response in the absence of movement is induced by physostigmine. Both responses are blocked with scopolamine. Lesions of the medial septal nucleus abolish hippocampal theta waves induced by forced running or physostigmine.