Functional Analysis of V3A and Related Areas in Human Visual Cortex

Abstract

Using functional magnetic resonance imaging (fMRI) and cortical unfolding techniques, we analyzed the retinotopy, motion sensitivity, and functional organization of human area V3A. These data were compared with data from additional human cortical visual areas, including V1, V2, V3/VP, V4v, and MT (V5). Human V3A has a retinotopy that is similar to that reported previously in macaque: (1) it has a distinctive, continuous map of the contralateral hemifield immediately anterior to area V3, including a unique retinotopic representation of the upper visual field in superior occipital cortex; (2) in some cases the V3A foveal representation is displaced from and superior to the confluent foveal representations of V1, V2, V3, and VP; and (3) inferred receptive fields are significantly larger in human V3A, compared with those in more posterior areas such as V1. However, in other aspects human V3A appears quite different from its macaque counterpart: human V3A is relatively motionselective, whereas human V3 is less so. In macaque, the situation is qualitatively reversed: V3 is reported to be prominently motion-selective, whereas V3A is less so. As in human and macaque MT, the contrast sensitivity appears quite high in human areas V3 and V3A.

Automatic volumetric segmentation of human visual retinotopic cortex

“…The layout of the cortical areas is in agreement with previous fMRI (DeYoe et al, 1996;Engel et al, 1997;Sereno et al, 1995;Smith et al, 1998;Tootell et al, 1997), positron emission tomography (Fox et al, 1987;Hasnain et al, 1998Hasnain et al, , 2001), lesion studies (Holmes, 1945;Horton and Hoyt, 1991;Wong and Sharpe, 1999), and cytoarchitectonic maps of Brodmann's area 17 and 18 (Amunts et al, 2000;Clarke and Miklossy, 1990).…”

“…The visual field sign pattern is in accordance with previous studies identifying visual areas (Sereno et al, 1995;DeYoe et al, 1996;Engel et al, 1997;Tootell et al, 1997;Smith et al, 1998). In all subjects visual areas V1, V2, V3/VP, V4v, and V3A could be identified.…”

“…These results were replicated by DeYoe et al (1996) and Engel et al (1997), also utilizing a cortical surface-based analysis but manually distinguishing the borders based on polar-angle information. Further phase-encoded mapping studies with modifications of the stimulus revealed visual areas V3A (DeYoe et al, 1996;Tootell et al, 1997Tootell et al, , 1998c, V3B (Press et al, 2001;Smith et al, 1998), V7 (Mendola et al, 1999;Press et al, 2001;Tootell et al, 1998a,c;Tootell and Hadjikhani, 2001), V8 , a putative homologue of the lateral intraparietal area (LIP) (Sereno et al, 2001), and retinotopic organization in human MT/V5 (Huk et al, 2002).…”

Differential human brain activation by vertical and horizontal global visual textures

“…These areas have all been previously described (e.g. Tootell et al 1997). We did not attempt to identify retinotopic areas in more anterior regions.…”

“…Human V3A has mainly been investigated with respect to its motion sensitivity see e.g. (Tootell et al 1997;Braddick et al 2000;Liu et al 2004;Aspell et al 2005;Koyama et al 2005); however, it is also known to be important in form processing (Schira et al 2004). Neurons in V3A have relatively large receptive Welds and contain a complete, contiguous representation of the visual Weld, making them potentially well-suited for an involvement in form integration.…”