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Sabrina Pitzalis, Marty Sereno, Giorgia Committeri, Patrizia Fattori, Gaspare Galati, Annalisa Tosoni, Claudio Galletti; The Human Homologue of Macaque Area V6A. Journal of Vision 2012;12(9):420. doi: 10.1167/12.9.420.
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© ARVO (1962-2015); The Authors (2016-present)
In monkey, the caudal part of the superior parietal lobule is occupied by extrastriate visual area V6, in the ventral part and fundus of the parieto-occipital sulcus (POs), and by visuomotor area V6A, on the anterior bank of the POs, dorsal and anterior to V6 (Galletti et al 1996). In contrast to V6, which has a retinotopic map of the contralateral visual field, V6A represents both contra- and ipsilateral visual fields and is less well retinotopically organized. The central 20°-30° of the visual field are mainly represented dorsally (V6Ad) and the periphery ventrally (V6Av), at the border with V6, and the contralateral lower visual field is over-represented in V6A, particularly in area V6Av. Both sectors of area V6A also contains arm movement-related cells, active during spatially-directed reaching movements (Gamberini et al., 2011). We previously mapped the retinotopic organization of area V6 in human (Pitzalis et al., 2006). Here, we used phase-encoded fMRI, cortical flattening, wide-filed retinotopic mapping, and fMRI responsiveness to finger pointing movements, to recognize human area V6A among the areas that surround V6. The new region borders V6 anteriorly but is distinct from it, with a clear over-representation of the contralateral lower visual field as well as of the periphery, similar to macaque area V6A. The new region shows a tendency for eccentricity to increase moving ventrally, again as in macaque V6A. Functional mapping revealed that the new region, but not V6, responds to pointing movements, as with macaque V6A. Based on similarity in position, retinotopic properties, functional organization and relationship with the neighbouring extrastriate visual areas, we suggest that new cortical region found here is the human homolog of macaque area V6A.
Meeting abstract presented at VSS 2012
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