Visual Deficits After Lesions of Brain Stem Tegmentum in Cats

Animals appear by gross tests to be blinded by certain lesions restricted entirely to the region of the upper brain stem. I have earlier observed such an effect in several cats which had sustained bilateral damage in the region of the optic tectum. Similar findings have been described for the monkey by Schreiner⁸and for the chimpanzee by Porter and Rioch.⁵Lillian Blake described marked disturbances of performance on visually learned tasks after lesions described as restricted to the superior colliculi in the cat.¹Sperry and associates, on the other hand, found only mild disturbances on tests of visual perception in three cats with subtotal lesions of superior colliculi.⁹Rosvold and others also failed to demonstrate any deficit in visual learning after bilateral lesions destroying up to 80% of the superior colliculus bilaterally in the monkey.⁷Ferrier and Turner, in studies of monkey superior colliculus