The superior colliculus and higher visual functions in the monkey

Abstract

Monkeys were tested on a battery of visual discrimination problems before and after aspiration lesions of the superior colliculi. Additional animals were given striate cortex ablations prior to or simultaneous with ablations of the colliculi, and tested before and after the combined lesions and interoperatively where possible. The results confirm earlier findings that collicular ablation produces no deficit in oculomotor function in alert monkeys, and further demonstrate that there are no impairements on formal tests of total flux, flicker, pattern, color, or visual movement detection discriminations. Collicular destruction does result in a reliable impairement of rate discrimination, however, which in the 7 animals studied was subject to considerable recovery. Prior and simultaneous partial striate cortex lesions potentiate these deficits severely and to the same degree. Complete striate ablations alone produce severe and well known visual impairments which do not, however, include significant impairment of flicker discrimination or CFF threshold. Addition of collicular ablation does abolish the capacity for a simple flicker discrimination, but even these severely impaired animals are capable of differential responses to changes in total luminous flux.