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Soojin Park, Katrina Ferrara, Barbara Landau; Impaired behavioral and neural sensitivity to boundary cues in Williams syndrome. Journal of Vision 2015;15(12):115. doi: https://doi.org/10.1167/15.12.115.
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Boundaries are fundamental features that define a scene. However, not all boundaries are equally effective for navigation. For example, when preschoolers are disoriented and have to reorient by a flat boundary (e.g., a mat), they are unable to use geometry and will randomly search the four corners of the mat. However, when the mat is replaced by a curb 2 cm in height, they demonstrate geometric sensitivity by constraining their searches to the correct corner and its rotational equivalent (Lee & Spelke, 2011). This highlights children’s exceptional sensitivity to boundaries that create subtle alterations in geometry. In the present study, we ask whether this sensitivity could be impaired by genetic defect using both behavioral and fMRI methods. Williams syndrome (WS) is a disorder resulting in abnormalities of hippocampal and parietal areas of the brain known to be involved in reorientation. WS children ages 4-12 years (n = 7) and adults ages 22-35 years (n = 5) were tested in three arrays defined by different boundary cues (mat, curb, and full wall). In contrast to typically developing (TD) children, both children and adults with WS randomly searched the 4 corners of the curb, and only geometrically reoriented within full walls. These data demonstrate that the WS reorientation mechanism is fragile, in that it requires the input of especially salient presentation of geometric layout. In a previous fMRI experiment (Ferrara & Park, VSS 2013), we found that the parahippocampal place area in TD adults is sensitive to the presence of a minimal curb cue in visually presented artificial scenes. Analyses of fMRI data from 2 WS adults indicate that this sensitivity is diminished. Collectively, this research suggests that damage to human parietal and hippocampal areas stemming from a genetic deficit can result in impairment of behavioral and neural representation of boundary cues.
Meeting abstract presented at VSS 2015
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