Assessment of disturbances in internal time counting and emotional behavior in rats with lesions to the striatum and hippocampus.

Bilateral electrolytic lesioning of the striatum led to a delay in the acquisition of a conditioned reflex to time, along with an anxiogenic effect and disturbances to the normal relationship between the level of anxiety and chronometric ability. These changes progressed with increases in the size of the destruction zone in the striatum. Combined surgery consisting of lesions to the striatum and hippocampus, like hippocampectomy alone, completely eliminated the ability to count time regardless of the size of brain lesions. The anxiogenic effect was greater in animaLs with combined procedures. Thus, the striatum and hippocampus are involved to different extents in the mechanism of internal time counting. The two structures function synergistically.