The human homologue of macaque area V6A

• Published in: NeuroImage (Orlando, Fla.) Fla.), 2013-11, Vol.82, p.517-530
• Main Authors: Pitzalis, S., Sereno, M.I., Committeri, G., Fattori, P., Galati, G., Tosoni, A., Galletti, C.
• Format: Article
• Language: English
• Subjects: Adult; Animals; Biological and medical sciences; Brain; Brain Mapping; Cortical flattening; Dorsal visual stream; Extrastriate areas; Female; Fundamental and applied biological sciences. Psychology; Humans; Image Processing, Computer-Assisted; Inventory; Macaca; Magnetic Resonance Imaging; Male; Methods; Parieto-occipital cortex; Photic Stimulation; Vertebrates: nervous system and sense organs; Visual Cortex - anatomy & histology; Visual Pathways - anatomy & histology; Visual topography
• ISSN: 1053-8119; 1095-9572
• DOI: 10.1016/j.neuroimage.2013.06.026

In macaque monkeys, V6A is a visuomotor area located in the anterior bank of the POs, dorsal and anterior to retinotopically-organized extrastriate area V6 (Galletti et al., 1996). Unlike V6, V6A represents both contra- and ipsilateral visual fields and is broadly retinotopically organized (Galletti et al., 1999b). The contralateral lower visual field is over-represented in V6A. The central 20°–30° of the visual field is mainly represented dorsally (V6Ad) and the periphery ventrally (V6Av), at the border with V6. Both sectors of area V6A contain arm movement-related cells, active during spatially-directed reaching movements (Gamberini et al., 2011). In humans, we previously mapped the retinotopic organization of area V6 (Pitzalis et al., 2006). Here, using phase-encoded fMRI, cortical surface-based analysis and wide-field retinotopic mapping, we define a new cortical region that borders V6 anteriorly and shows a clear over-representation of the contralateral lower visual field and the periphery. As with macaque V6A, the eccentricity increases moving ventrally within the area. The new region contains a non-mirror-image representation of the visual field. Functional mapping reveals that, as in macaque V6A, the new region, but not the nearby area V6, responds during finger pointing and reaching movements. Based on similarity in position, retinotopic properties, functional organization and relationship with the neighboring extrastriate visual areas, we propose that the new cortical region is the human homologue of macaque area V6A. •We used fmri, cortical surface-based analysis and wide-field retinotopic mapping.•We defined a region with retinotopy and position similar to those of macaque V6A.•We tested whether the new region has functional properties as macaque V6A.•The new region responds to pointing movements requiring wrist orientation changes.•The comparison with monkey data suggest that the new region is the human area V6A.