Photically evoked unit activity in the tectum opticum of the squirrel monkey

Abstract

Abstract Visually evoked unit responses of the tectum were studied in the squirrel monkey. The results showed that the superior colliculus had a definite functional laminar organization. Units responding to diffuse light were found in the upper part of the stratum griseum superficiale, units having antagonistically segregated receptive fields in the middle portion, and units sensitive to moving objects in the lower portion as well as in the stratum opticum. Retinotopic projection was also observed. The pretectal region contained mainly “tonic‐on” and “inhibitory” units. No specific localization was observed in the distribution of these units.