TOPOGRAPHY OF VISUAL-CORTEX CONNECTIONS WITH FRONTAL EYE FIELD IN MACAQUE - CONVERGENCE AND SEGREGATION OF PROCESSING STREAMS

The primate visual system consists of at least two processing streams, one passing ventrally into temporal cortex that is responsible for ob ject vision, and the other running dorsally into parietal cortex that is responsible for spatial vision, How information from these two stre ams is combined for perception and action is not understood, Visually guided eye movements require information about both feature identity a nd location, so we investigated the topographic organization of visual cortex connections with frontal eye field (FEF), the final stage of c ortical processing for saccadic eye movements, Multiple anatomical tra cers were placed either in parietal and temporal cortex or in differen t parts of FEF in individual macaque monkeys. Convergence from the dor sal and ventral processing streams occurred in lateral FEF but not in medial FEF, Certain extrastriate areas with retinotopic visual field o rganizations projected topographically onto FEF, The dorsal bank of th e superior temporal sulcus projected to medial FEF; the ventral bank, to lateral FEF, and the fundus, throughout FEF, Thus, lateral FEF, whi ch is responsible for generating short saccades, receives visual affer ents from the foveal representation in retinotopically organized areas , from areas that represent central vision in inferotemporal cortex an d from other areas having no retinotopic order, In contrast, medial FE F, which is responsible for generating longer saccades, is innervated by the peripheral representation of retinotopically organized areas, f rom areas that emphasize peripheral vision or are multimodal and from other areas that have no retinotopic order or are auditory.