Abstract
Environmental boundaries play a critical role in defining spatial geometry and restrict our movement within an environment. Developmental research with 4-year-olds shows that children are able to reorient themselves by the geometry of a curb that is only 2 cm high, but fail to do so when the curb boundary is replaced by a flat mat on the floor (Lee & Spelke, 2011). In this talk, we will present evidence that such fine-grained sensitivity to a 3D boundary cue is represented in visual scene processing regions of the brain, parahippocampal place area (PPA) and retrosplenial cortex (RSC). First, we will present univariate and multivoxel pattern data from both regions to suggest that they play complementary roles in the representation of boundary cues. The PPA shows disproportionately strong sensitivity to the presence of a slight vertical boundary, demonstrating a neural signature that corresponds to childrens behavioral sensitivity to slight 3D vertical cues (i.e., the curb boundary). RSC did not display this sensitivity. We will argue that this sensitivity does not simply reflect low-level image differences across conditions. Second, we investigate the nature of boundary representation in RSC by parametrically varying the height of boundaries in the vertical dimension. We find that RSCs response matches a behavioral categorical decision point for the boundarys functional affordance (e.g., whether the boundary limits the viewers potential navigation or not). Collectively, this research serves to highlight boundary structure as a key component of space that is represented in qualitatively different ways across two scene-selective brain regions.
Meeting abstract presented at VSS 2016