The Output of the Cat Visual Cortex

Abstract

Important laminar differences in cortical output have been established: the deep layers (V and VI) project subcortically, while the superficial layers give rise to commissural (mainly layer III) and associative (layers II and III) projections (Gilbert and Kelly, 1975; Toyama et al., 1969 a). While this distinction is quite clear in area 17, the picture is less clear for areas 18 and 19 of which the deep and superficial layers project to area 17 (Bullier and Kennedy, personal communication). The subcortical targets include the pons, the superior colliculus, and the pretectum, the claustrum, the LGN, the pulvinar, and the lateralis posterior. The main cortical targets are other visual cortical areas: the lateral suprasylvian areas and areas 20 and 21. Relatively few projections to non-visual areas have been demonstrated. The subcortical projections of the visual cortex have been well studied and their function begins to be understood: most of them are related to the control of body motion and oculomotor function by vision. Relatively little is known of the corticocortical projections, which probably are important for further processing of the visual images and hence for visual perception.