Abstract
Despite the critical role of occipitotemporal cortex (OTC) in visual recognition, children undergoing cortical resection of OTC show remarkably intact post-operative visual recognition behaviors. In fact, the profile of neural selectivity for visual categories has been shown to be comparable in pediatric OTC resection patients and healthy age-matched controls. This suggests potential underlying neuroplasticity, but it remains unclear whether the integrity of neural representations within a category-selective region is fully intact following resection. With functional magnetic resonance imaging (fMRI), the hemodynamic response is typically suppressed upon repeated presentation of the same stimulus exemplar, a phenomenon termed repetition suppression (RS). RS can thus be used as an inferential measure of the neural computations underlying stimulus individuation. If pediatric OTC resection patients were to evince typical RS patterns in preserved cortex, this would support the claim of post-operative plasticity of higher-level vision. To test this, pediatric patients post-surgery, which did or did not include OTC, and healthy age-matched controls participated in an fMRI study. In the adaptation/RS paradigm, in separate functional runs, participants viewed blocks of either the same visual exemplar presented 12 times (“same” condition) or 12 unique exemplars (“different” condition), each for faces, objects, and words (and an intermediate condition as well). In addition, participants completed an independent functional localizer study to define regions of interest (ROI) for face-, object-, and word-selectivity. RS was approximated as the difference in the average beta weight for the different and same conditions, within each ROI as well as in whole-brain analysis. Across stimulus categories and ROIs, patients (OTC and non-OTC) exhibited RS profiles within the control distribution (confirmed with Crawford statistics for neuropsychological single-subject case studies). These findings suggest that post-resection, residual cortex can fulfill the necessary computations for visual exemplar individuation, potentially explaining the patients’ post-operative behavioral compensations.