Retinotopic Organization of Human Ventral Visual Cortex

Abstract

Functional magnetic resonance imaging studies have shown that human ventral visual cortex anterior to human visual area V4 contains two visual field maps, VO-1 and VO-2, that together form the ventral occipital (VO) cluster . This cluster is characterized by common functional response properties and responds preferentially to color and object stimuli. Here, we confirm the topographic and functional characteristics of the VO cluster and describe two new visual field maps that are located anterior to VO-2 extending across the collateral sulcus into the posterior parahippocampal cortex (PHC). We refer to these visual field maps as parahippocampal areas PHC-1 and PHC-2. Each PHC map contains a topographic representation of contralateral visual space. The polar angle representation in PHC-1 extends from regions near the lower vertical meridian (that is the shared border with VO-2) to those close to the upper vertical meridian (that is the shared border with PHC-2). The polar angle representation in PHC-2 is a mirror reversal of the PHC-1 representation. PHC-1 and PHC-2 share a foveal representation and show a strong bias toward representations of peripheral eccentricities. Both the foveal and peripheral representations of PHC-1 and PHC-2 respond more strongly to scenes than to objects or faces, with greater scene preference in PHC-2 than PHC-1. Importantly, both areas heavily overlap with the functionally defined parahippocampal place area. Our results suggest that ventral visual cortex can be subdivided on the basis of topographic criteria into a greater number of discrete maps than previously thought.

Functional Heterogeneity in Posterior Parietal Cortex Across Attention and Episodic Memory Retrieval

“…Just as recent studies in visual (Brewer et al 2005;Larsson and Heeger 2006;Sayres and Grill-Spector 2008;Arcaro et al 2009;Kolster et al 2010;Grill-Spector 2010, 2011;Rauschecker et al 2011), frontal (Hagler and Sereno 2006;Kastner et al 2007), and parietal cortex (Levy et al 2007;Swisher et al 2007) illustrate the benefit of multiple experimental techniques for clarifying the complexity of neural organization in both topographic and nontopographic areas, the present study demonstrates the generalizability of this approach to regions involved in multiple aspects of memory and attention. In particular, our results reveal heterogeneity across topographically organized PPC subregions, with 1) IPS0 displaying a distinct pattern of activity from IPS4, IPS5, and SPL1, and 2) IPS1-3 not exhibiting differential responses across retrieval conditions (though future studies with additional power are required to draw definitive conclusions about the relative effects of retrieval outcomes on responses in these areas).…”

Top-down attention switches coupling between low-level and high-level areas of human visual cortex

“…We performed phase-encoded retinotopic mapping using standard stimuli and procedures (23). A rotating wedge of a flickering colored checkerboard was used to map polar angle (two runs each of clockwise and counterclockwise rotation), and an expanding and contracting ring of the same checkerboard was used to map eccentricity (one run each of expansion and contraction).…”

“…Phase estimates from clockwise/counterclockwise and expansion/contraction were averaged to account for hemodynamic lag. We projected these values onto the cortical surface and determined occipital ROIs according to the relative locations of polar-angle reversals and foveally stimulated regions (23). We defined the FFA and PPA ROIs from the face/scene localizer as the peak voxel in right ventral temporal cortex that was most selective for faces (face blocks > scene blocks) and scenes (scene blocks > faces blocks), respectively.…”

“…In occipital cortex, we focus on human area V4 because of its proximity to FFA and PPA-in terms of both physical distance (4,23) and representational complexity (24)-and because V4 is strongly affected by attention (8,9,11,15). Thus, if attention operates by regulating interactions within visual cortex, then attention to a category should be associated with increased background connectivity between V4 and the goal-relevant region of ventral temporal cortex.…”

Brain bases of the automaticity via visual search task

“…Ventral aspects of the visual cortex, extending to IT, contain visual field maps related to processing object recognition. In this portion human V4 (hV4), ventral occipital visual field maps VO-1 and VO-2 are found, which are located adjacent to the ventral portion of V3 (Wandell and Winawer 2011), and anterior to VO-2 are the parahippocampal visual field maps PHC-1 and PHC-2 (Arcaro, McMains, Singer and Kastner, 2009). Color processing has been linked to hV4 and ventral occipital maps; however, the other ventral maps are related to processing forms, such as objects or faces, words or places.…”