Retinotopy Versus Face Selectivity in Macaque Visual Cortex
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Retinotopy versus Face Selectivity in Macaque Visual Cortex The MIT Faculty has made this article openly available. Please share how this access benefits you. Your story matters. Citation Rajimehr, Reza, Natalia Y. Bilenko, Wim Vanduffel, and Roger B. H. Tootell. “Retinotopy Versus Face Selectivity in Macaque Visual Cortex.” Journal of Cognitive Neuroscience 26, no. 12 (December 2014): 2691–2700. © 2014 Massachusetts Institute of Technology As Published http://dx.doi.org/10.1162/jocn_a_00672 Publisher MIT Press Version Final published version Citable link http://hdl.handle.net/1721.1/92520 Terms of Use Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. Retinotopy versus Face Selectivity in Macaque Visual Cortex Reza Rajimehr1,2, Natalia Y. Bilenko1, Wim Vanduffel1,3, and Roger B. H. Tootell1 Abstract ■ Retinotopic organization is a ubiquitous property of lower- Distinct subregions within face-selective patches showed tier visual cortical areas in human and nonhuman primates. In either (1) a coarse retinotopic map of eccentricity and polar macaque visual cortex, the retinotopic maps extend to higher- angle, (2) a retinotopic bias to a specific location of visual order areas in the ventral visual pathway, including area TEO field, or (3) nonretinotopic selectivity. In general, regions in the inferior temporal (IT) cortex. Distinct regions within IT along the lateral convexity of IT cortex showed more overlap cortex are also selective to specific object categories such as between retinotopic maps and face selectivity, compared with faces. Here we tested the topographic relationship between regions within the STS. Thus, face patches in macaques can be retinotopic maps and face-selective patches in macaque visual subdivided into smaller patches with distinguishable retino- cortex using high-resolution fMRI and retinotopic face stimuli. topic properties. ■ INTRODUCTION has been recently challenged by the demonstration of small Visual cortical areas are typically defined on the basis of receptive fields in anterior IT cortex (DiCarlo & Maunsell, differences in histology (cytoarchitecture and myelo- 2003; Op De Beeck & Vogels, 2000). architecture), anatomical connections, functional proper- How do the retinotopic maps in IT cortex relate to ties, and retinotopic organization (Felleman & Van Essen, the functionally defined category-selective areas? Neuro- 1991). In early visual areas (e.g., V1, V2, V3), the retino- imaging studies in human and macaque have reported topic maps can be reliably used to distinguish the borders that distinct regions in IT cortex are selective to specific ob- between areas (Fize et al., 2003; Brewer, Press, Logothetis, ject categories such as faces (e.g., Tsao, Freiwald, Knutsen, & Wandell, 2002; DeYoe et al., 1996; Sereno et al., 1995; Mandeville, & Tootell, 2003; Kanwisher, McDermott, & Engel et al., 1994; Gattass, Sousa, & Gross, 1988). However, Chun, 1997). Malach and colleagues (Hasson, Harel, Levy, the retinotopic borders are less clear at progressively & Malach, 2003; Malach, Levy, & Hasson, 2002; Levy, higher stages of the ventral visual pathway (Kravitz, Vinson, Hasson, Avidan, Hendler, & Malach, 2001) tested the rela- & Baker, 2008). An earlier proposal suggested that the infe- tionship between retinotopic maps and face-selective rior temporal (IT) cortex in macaque monkeys includes a areas in human visual cortex and reported a foveal bias retinotopically organized area TEO, plus nonretinotopic in these areas (relative to a peripheral bias in the adjacent areas in TE (Boussaoud, Desimone, & Ungerleider, 1991; place-selective areas)—although not an explicit retinotopic Ungerleider & Desimone, 1986). Recent fMRI studies have map. However, the spatial resolution of fMRI images was confirmed retinotopy and coding of position in posterior low in those studies, and it is well known that fine-scale IT cortex in humans, perhaps corresponding to area TEO retinotopic details are blurred in low-resolution maps in macaques (Carlson, Hogendoorn, Fonteijn, & Verstraten, (see Discussion). 2011; Cichy, Chen, & Haynes, 2011; Kravitz, Kriegeskorte, & Recent fMRI studies in humans have reported a de- Baker, 2010; Strother, Aldcroft, Lavell, & Vilis, 2010; Arcaro, tailed retinotopic organization in “object-selective” lateral McMains, Singer, & Kastner, 2009; Sayres & Grill-Spector, occipital cortex (Sayres & Grill-Spector, 2008; Larsson & 2008; Schwarzlose, Swisher, Dang, & Kanwisher, 2008; Heeger, 2006), “scene-selective” parahippocampal cortex Larsson & Heeger, 2006; Brewer, Liu, Wade, & Wandell, (Arcaro et al., 2009), and “body-selective” regions (Porat, 2005). However, the lack of positional information in TE Pertzov, & Zohary, 2011; Weiner & Grill-Spector, 2011). However, there has been no evidence for a detailed retino- topy in human face-selective area FFA, and the current literature has emphasized only on a distributed representa- 1Harvard Medical School, 2Massachusetts Institute of Technology, tion of positional information in this area (e.g., Schwarzlose 3K.U. Leuven Medical School et al., 2008). © 2014 Massachusetts Institute of Technology Journal of Cognitive Neuroscience 26:12, pp. 2691–2700 doi:10.1162/jocn_a_00672 Despite numerous studies in humans, the relationship Data Analysis between retinotopy and category selectivity has not yet Functional and anatomical data were preprocessed and been tested in other species. Such tests would have analyzed using FreeSurfer and FS-FAST (surfer.nmr. important implications for cross-species comparison of mgh.harvard.edu/). For each subject, the inflated cortical category-selective areas (see Discussion). Here we used surfaces were reconstructed based on anatomical images. high-resolution fMRI and face-based retinotopic stimuli All functional images were motion-corrected, spatially to test the topographic relationship between retinotopic smoothed using a 3-D Gaussian kernel (1 mm HWHM), maps and face-selective patches in awake macaques. The and normalized across scans. The estimated hemo- results suggest that retinotopy is not an “all-or-none” prop- dynamic response was defined by a γ function, and then erty in the face patches. In fact, face-selective patches in the average signal intensity maps were calculated for IT and frontal cortex contain topographically distinct each stimulus condition. Voxel-wise statistical tests were subregions, each with a specific retinotopic property. The conducted by computing contrasts based on a univariate retinotopic subregions of the face patches could be in- general linear model. To avoid sampling gaps in the volved in coding the spatial location of faces. (high-resolution) monkey fMRI, we averaged the func- tional activities from all voxels located within the gray matter along the surface normal. To optimally visualize and measure the cortical representations, the signifi- METHODS cance levels were projected onto the inflated cortex after Subjects a rigid coregistration of functional and anatomical vol- Two juvenile (4–6 kg) male rhesus monkeys (Macaca umes. In each monkey, the functional maps were spatially mulatta) were tested in fMRI experiments. Surgical de- normalized across scan sessions using a spherical trans- tails and the training procedure for monkeys have been formation and then averaged using a fixed-effects model. described elsewhere (Tsao et al., 2003; Vanduffel et al., For the ROI analysis, all voxels within a given face patch “ ” 2001). All experimental procedures conformed to NIH were labeled based on a face-versus-place localizer, and guidelines and were approved by Massachusetts General then the average percent signal change was calculated for Hospital animal protocols. different retinotopic conditions in each ROI. Visual Stimuli Imaging Procedures Stimuli were generated on a PC (Windows XP) and pre- Monkeys were scanned in a 3T horizontal bore magnet sented via LCD projector (Sharp XG-P25, Osaka, Japan, (Siemens Allegra, Malvern, PA). A radial surface coil (11 cm 1024 × 768 pixels resolution, 60 Hz refresh rate) onto a diameter) and gradient-echo EPI sequence were used rear-projection screen. Matlab 7.0 and Psychophysics Tool- for functional imaging (repetition time = 3000 msec, box (psychtoolbox.org/) were used to program the visual echo time = 24 msec, flip angle 90°, 1.25 mm isotropic presentation codes. voxels, and 45 coronal slices). To increase fMRI sensitivity The retinotopic stimuli were based on face mosaics in the awake monkey scans (to compensate for smaller (naturalistic “group photographs”), which were presented voxels), we used an exogenous contrast agent (MION; within retinotopically limited apertures, on a black back- 8–10 mg/kg iv). Relative to conventional BOLD imaging ground (Figure 1). The retinotopic apertures included at 3T, the MION imaging triples the contrast/noise ratio (1) a foveal disk (1.5° radius), (2) a peripheral annulus and gives better localization within the gray matter (Leite (5° inner radius and 10° outer radius), (3) an upper vertical et al., 2002; Vanduffel et al., 2001). A 3-D MP-RAGE meridian wedge (10° radius and 60° angle), (4) a lower sequence (0.35 mm isotropic voxels) was also used for vertical meridian wedge (10° radius and 60° angle), (5) a high-resolution anatomical imaging while the monkeys left horizontal meridian wedge (10° radius and 30° angle), were anesthetized. and (6) a right horizontal meridian wedge (10° radius and Throughout the functional