Functional magnetic resonance imaging (fMRI) studies identify areas responding selectively to images of faces and body parts compared to a variety of control objects throughout ventral temporal and lateral occipitotemporal cortices (VTC and LOTC, respectively). Previous research indicates that the location of each region is variable relative to both gross anatomical landmarks, as well as to other high-level visual areas. Using higher-resolution fMRI scanning methods, we conducted a series of experiments revealing that the fine-scale spatial organization of face and limb selectivity is much more consistent than once thought. These experiments reveal a topographic organization of face- and limb-selective regions extending from LOTC to VTC where each high-level region is defined by a combination of anatomical and functional boundaries separating them from neighboring regions just millimeters away. We propose a multi-factor organization framework resulting from these empirical measurements where any region in human high-level visual cortex can be defined using the following criteria: 1) precise anatomical location, 2) preserved spatial relationship among functional regions, 3) preserved relationship relative to known visual field maps, and 4) reliable functional differences among regions. Methodologically, we demonstrate how these organizational features allow consistent parcellation of cortical regions across subjects. Theoretically, we refer to this inter-related structure of multiple maps as cortical tiling and hypothesize that tiling is a universal organizational strategy of the brain. Finally, we discuss computational benefits of this organization serving to accommodate multidimensional information in a concentrated neural territory to increase the repertoire, flexibility, and efficiency of visual processing.
Meeting abstract presented at VSS 2013