Eccentricity-specific dissociation of visual functions in patients with lesions of the central visual pathways

Abstract

THE human retina projects not only to the lateral geniculate bodies and from there to the visual cortices, but in a parallel fashion to several other subcortical centres as well. One such centre is the superior colliculus, and it has been suggested that a rudimentary discrimination capacity of the locus of visual stimuli may be mediated by this structure¹. Results of anatomical studies with subhuman primates indicate that the macular region does not project to the superior colliculus^2,3 (or that it is represented by a different population of retinal fibres which have not yet been identified by anatomical techniques⁴). The macular region seems to project only to the lateral geniculate bodies and from there to visual cortices, whereas the retinal periphery projects to several subcortical centres. This raises the question of whether a similar dissociation of projection between the central and peripheral retina also can be found in the human visual system. We present data obtained from patients with lesions of the central visual pathways which indeed suggest such a dissociation.