HYPERACTIVITY, APHAGIA AND MOTOR DISTURBANCE FOLLOWING LESIONS OF SUPERIOR COLLICULUS AND UNDERLYING TEGMENTUM IN RATS

To investigate possible nonvisual functions of the superior colliculus, hooded rats with extensive collicular lesions were tested for disturbances of activity, feeding, and motor performance. Their pattern of behavior in the open field was abnormal, with markedly increased locomotor activity accompanied by a decrease in rearing and defecation. Damage to the deep layers of the superior colliculus may have been involved in these effects. Feeding and motor disturbances were also observed, but these were probably caused, at least in part, by invasion of the dorsal tegmentum underlying the colliculus; the aphagia, which appeared to have a strong motor component, was much worse in animals with substantial tegmental damage. The superior colliculus in rats may be involved in the regulation of activity, exploration, and possibly fearful behavior. It is unclear why large lesions of the superior colliculus increase activity in rats, but apparently reduce it in other species. © 1979 Academic Press, Inc.