The consequences of optic neuritis

Abstract

Vision relies on dual parallel pathways originating in the retina and extending throughout cerebral cortex that support the separate processing of visual form and motion. In this issue of Neurology ®, Raz et al.1 report a new and important consequence of that organization: optic neuritis (ON) can have prolonged effects on visual motion processing despite its more conventionally transient effects on visual form processing. The recognition of dual visual processing pathways began with the work of Kleist,2 who combined clinical and experimental observations to discern the separate cortical localization of lesions that cause form vs motion processing impairments. Later neuroanatomic and neurophysiologic studies established the existence of X and Y retinal ganglion cells.3 The X ganglion cells dominated the central retina and provided a more slowly conducting high spatial resolution input to the parvocellular lateral geniculate. The Y ganglion cells dominated the peripheral retina and provided a fast conducting, low resolution input to the magnocellular lateral geniculate. Studies of nonhuman primates then extended this duality for object form processing in poststriate cortical pathways: temporal extrastriate areas for object recognition and parietal extrastriate areas for motion …