Linking dorsal association cortex and spatial vision

The visual functions of parietotemporal cortex were revealed in electrical stimulation and lesion studies (Ferrier, 1876). These findings were overshadowed by the mapping of occipital visuotopy (Holmes, 1918; Inouye, 1909). Interest in extrastriate vision was sustained by experimental evidence of visual function after striate removal (Kluver, 1936) and by clinical evidence of differential parietal and temporal involvement in spatial and object vision (Kleist, 1935).

Updated approaches revealed visual evoked electrical activity in extrastriate cortex (Doty et al., 1964) and striate projections into these areas (Cragg, 1969; Zeki, 1969). Lesion analysis put these findings in the context of dorsal extrastriate specialization for spatial perception and contrasted it with ventral extrastriate specialization for object identification (Ungerleider and Brody, 1977; Ungerleider and Mishkin, 1982). Lesion studies suggested that the colliculo-pulvino-parietal visual pathway (Humphrey and Weiskrantz, 1967; Schneider, 1969) supports behavioral responses to visual motion (Doty, 1973; Pasik et al., 1969). Thus, converging dorsal geniculostriate and colliculo-pulvino-parietal pathways combine to serve vision for spatial orientation (Trevarthan, 1968).

The behavioral relevance of this system was seen in patients with striate lesions causing blindsight (Sanders et al., 1974) and extrastriate lesions causing spatial deficits (Botez, 1975). Posterior parietal neurons were found to combine visuosensory and visuomotor signals in a manner that suggested involvement in extrapersonal space perception (Mountcastle, 1976). These findings linked visual motion processing, visuospatial perception, and dorsal extrastriate cortex in a way that provided the theoretical foundation of efforts to understand the cortical analysis of optic flow.