Abstract
Boundaries are fundamental features that define a scene and contribute to its geometric shape. Our previous research using fMRI demonstrates a distinct sensitivity to the presence of vertical boundaries in scene representation by the parahippocampal place area (PPA) in healthy adults (Ferrara & Park, 2014). In the present research, we show that this sensitivity to boundaries is impaired by genetic deficit. Studying populations with spatial disorders can provide insight to potential brain/behavior links that may be difficult to detect in healthy adults. We couple behavioral and neuroimaging methods to study individuals with Williams syndrome (WS), a disorder characterized by the deletion of 25 genes and severe impairment in a range of spatial functions. When both humans and animals are disoriented in a rectangular space, they are able to reorient themselves by metric information conveyed by the enclosures boundaries (e.g., long wall vs. short wall). Using this reorientation process as a measure, we find that individuals with WS are unable to reorient by a small boundary cue, in stark contrast to the behavior of typically developing (TD) children (Lee & Spelke, 2011). Using fMRI, we find a linked neural pattern in that the WS PPA does not detect the presence of a small boundary within a scene. Taken together, these results demonstrate that atypical patterns of reorientation correspond with less fine-grained representation of boundaries at the neural level in WS. This suggests that sensitivity to the geometry of boundaries is one of the core impairments that underlies the WS reorientation deficit.
Meeting abstract presented at VSS 2016