The effects of bilateral frontal eye-field, posterior parietal or superior collicular lesions on brightness thresholds in the rhesus monkey

Abstract

Monkeys were trained to press whichever of two panels showed a small, circular, luminous stimulus. Their brightness thresholds were measured by decreasing the luminance of this stimulus, titrating their performance to the 75% correct level, and averaging over 1000 trials. Both frontal eye-field and superior collicular lesions produced a small but significant rise in threshold when measured 1–2 weeks post-operatively. The rise had disappeared by the sixth post-operative week. Brightness thresholds were not affected by posterior parietal lesions.