Deficits in luminous flux discimination by cats with lesions of the superior colliculus-pretectum.

(1) Intact cats and cats relearning or initially learning after bilateral ablation of the superior colliculus-pretectum were trained on a simple flux discrimination in a straight maze where the stimuli were either immediately side by side at the end of the runway or were separated by an opaque barrier. (2) After ablation of the superior colliculus-pretectum, each preoperatively trained cat had a significant deficit in retention of the luminous flux discrimination regardless of whether or not the stimuli were separated by a barrier or whether the correct stimulus was darker or lighter than the incorrect stimulus. (3) Under each of the different training conditions, every cat learning the flux discrimination initially after ablation of the superior colliculus-pretectum was retarded in comparison with intact cats. (4) The severity of the postoperative learning deficit correlated highly with the total extent of the lesion in the superior colliculus and pretectum.