Topographic organization in and near human visual area V4.
The existence and location of a human counterpart of macaque visual area V4 are disputed. To resolve this issue, we used functional magnetic resonance imaging to obtain topographic maps from human subjects, using visual stimuli and tasks designed to maximize accuracy of topographic maps of the fovea and parafovea and to measure the effects of attention on topographic maps. We identified multiple topographic transitions, each clearly visible in > or = 75% of the maps, that we interpret as boundaries of distinct cortical regions. We call two of these regions dorsal V4 and ventral V4 (together comprising human area V4) because they share several defining characteristics with the macaque regions V4d and V4v (which together comprise macaque area V4). Ventral V4 is adjacent to V3v, and dorsal V4 is adjacent to parafoveal V3d. Ventral V4 and dorsal V4 meet in the foveal confluence shared by V1, V2, and V3. Ventral V4 and dorsal V4 represent complementary regions of the visual field, because ventral V4 represents the upper field and a subregion of the lower field, whereas dorsal V4 represents lower-field locations that are not represented by ventral V4. Finally, attentional modulation of spatial tuning is similar across dorsal and ventral V4, but attention has a smaller effect in V3d and V3v and a larger effect in a neighboring lateral occipital region.
Hansen
Kathleen A
KA
Department of Psychology and Wheeler Brain Imaging Center, University of California, Berkeley, Berkeley, California 94720, USA.
Kay
Kendrick N
KN
Gallant
Jack L
JL
D001931:Brain Mapping; D007839:Functional Laterality; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D010100:Oxygen / Q000097:blood; D010775:Photic Stimulation / Q000379:methods; D014793:Visual Cortex / Q000033:anatomy & histology* / Q000502:physiology; D014794:Visual Fields / Q000502:physiology*; D014795:Visual Pathways / Q000033:anatomy & histology
D010100:Oxygen