Human ventral temporal cortex (VTC) is critical for visual recognition. It is thought that this ability is supported by large-scale patterns of activity across VTC that contain information about visual categories. However, it is unknown how category representations in VTC are organized at the submillimeter scale and across cortical depths. To fill this gap in knowledge, we measured BOLD responses in medial and lateral VTC to images spanning 10 categories from five domains (written characters, bodies, faces, places, and objects) at an ultra-high spatial resolution of 0.8 mm using 7 Tesla fMRI in both male and female participants. Representations in lateral VTC were organized most strongly at the general level of domains (e.g., places), whereas medial VTC was also organized at the level of specific categories (e.g., corridors and houses within the domain of places). In both lateral and medial VTC, domain-level and category-level structure decreased with cortical depth, and downsampling our data to standard resolution (2.4 mm) did not reverse differences in representations between lateral and medial VTC. The functional diversity of representations across VTC partitions may allow downstream regions to read out information in a flexible manner according to task demands. These results bridge an important gap between electrophysiological recordings in single neurons at the micron scale in nonhuman primates and standard-resolution fMRI in humans by elucidating distributed responses at the submillimeter scale with ultra-high-resolution fMRI in humans.
Bibliographical noteFunding Information:
This work was supported by National Science Foundation GRFP to E.M.; National Eye Institute 1R01EY023915 to K.G.-S.; National Institutes of Health Grants P41 EB015894, P30 NS076408, S10 RR026783, and S10 OD017974-01 to K.N.K.; and W. M. Keck Foundation to K.N.K. 2004; Moutoussis and Zeki, 2002; Gaillard et al., 2006; Parvizi et al., 2012; Rangarajan et al., 2014). Studies of VTC have shown that ecological domains of objects, faces, body parts, characters, and places elicit clustered responses in predictable anatomical locations within VTC (Malach et al., 1995; Kanwisher et al., 1997; Aguirre et al., 1998; Epstein and Kanwisher, 1998; Grill-Spector
This work was supported by National Science Foundation GRFP to E.M.; National Eye Institute 1R01EY023915 to K.G.-S.;NationalInstitutesofHealthGrantsP41EB015894,P30NS076408,S10RR026783,andS10OD017974-01to K.N.K.; and W. M. Keck Foundation to K.N.K.
Copyright © 2020 the authors
- Cortical depth
- High-level visual cortex
- Ventral temporal cortex
- Visual categories
- Visual representations