Diurnal activity rhythm of rats with lesions of superior colliculus and visual cortex

¹ Psychophysiological Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts

The role of two central nervous visual structures. the superior colliculus and striate cortex, was investigated in the coordination of the day-night activity cycles of rats. While both normal rats and rats with bilateral lesions in superior colliculus or striate cortex showed higher rates of general activity at night than during the day, the brain-operated animals showed less difference than the normals. Decrease in nocturnal activity preference was considerable in the striate cortex lesion group in which mean destruction of tissue was as high as 91%, whereas in the superior colliculus similar effects were obtained with mean destruction of only 41% of tissue.