No abstract

Rats with hippoeampal lesions were found to be more active than normal and brain damaged controls. This hyperactivity was manifested in a greater number of light-beam interruptions in an activity cage and in increased running speed in an unbaitcd T maze. When placed in a situation involving inhibition of movement, Ss witli hippoeampal lesions were unable to inhibit movement to avoid shock.

No abstract

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.

Tolerance, manifested by a diminished electroencephalographic response at cortical and subcortical recording sites, was found in rats subjected to repeated systemic injections of morphine sulfate. Reversal of tolerance to morphine resulted from destruction of the medial thalamus.