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Julie Steinbrink, Charles Laymon, Bedda Rosario, Amy Nau; The Relationship of Specific Categorical Variables with PET Scan White Matter Activation in Blind and Control Subjects Using BrainPort. Invest. Ophthalmol. Vis. Sci. 2013;54(15):3412.
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The BrainPort is a visual prosthetic device where a video camera acts as an artificial sensory receptor to interact with a human-machine interface. The camera is aligned with the subject’s field of vision, and is connected to an intraoral electrode array on the surface of the tongue, allowing for interpretation of the immediate visual surroundings. We examined the relationship between subject demographic variables of blind subjects trained to use the BrainPort. Our objective was to determine how these variables related to areas of brain activation as seen by Positron Emission Tomography (PET) scans.
14 subjects with acquired blindness, 4 subjects who were congenitally blind, and 6 sighted blindfolded controls (n=10 females, n=16 males, age range 22-74) underwent 20 hours of structured training on the BrainPort. PET scans were run with fluorodeoxyglucose at baseline and after training - these scans were averaged together per subject. Data was warped and registered to the Montreal Neurologic Institute template to allow for voxel-wise group analysis. A multiple regression analysis of the PET scan data was performed with the statistical parametric mapping software SPM8. In this analysis, voxel-based values of the PET scans were compared with 5 different covariates: Age, Gender, Life-Ratio of Blindness, Sudden vs. Gradual Onset of Blindness, and Congenital vs. Non-congenital Blindness.
Significant differences were found in the occipital region when comparing Congenital vs. Non-congenital groups (p=0.017 cluster, p=0.070 peak). Significance levels were corrected for multiple comparisons using the family-wise-error method (p=0.10). Age, Gender, Life-Ratio, and Sudden vs. Gradual covariates did not show statistically significant relationships.
A significant relationship was seen between the Congenital vs. Non-congenital covariate and brain activation but our analysis failed to show a statistically significant relationship between other covariates under study and white matter activation. This suggests that the mechanisms of cross-modal activation in sensory substitution appear to be mediated by the same pathways irrespective of duration or temporal course of blindness in acquired blindness, but not in congenital blindness.
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