Subthalamic and mesencephalic locomotor regions: brain damage augments the importance of female movement for the display of sexual behavior in male rats.

Electrical stimulation of parts of the subthalamus and midbrain provokes coordinated locomotion. In this study we contrasted the sexual behavioral effects of electrolytic destruction of the subthalamic and mesencephalic "locomotor" regions in male rats. Bilateral electrolytic lesions of the subthalamic locomotor region (SLR) attenuated, and in some cases eliminated, male sexual behavior. Although some SLR lesioned males appeared to mate normally on some tests, these males did not mount females rendered hypokinetic by an injection of haloperidol. Males with mesencephalic locomotor region lesions mated normally with a normally active female but most, like males with SLR lesions, showed virtually no sexual responses towards hypokinetic females. Locomotor region damage apparently augments the importance of female movement for the display of male sexual behavior, and we suggest this may be related to an effect of brain damage on sexual motivation.