Motion and form coherence processing in individuals with cerebral visual impairment

Aim: Using a visual psychophysical paradigm, we sought to assess motion and form coherence thresholds as indices of dorsal and ventral visual stream processing respectively, in individuals with cerebral visual impairment (CVI). We also explored potential associations between psychophysical assessments and brain lesion severity in CVI. Method: Twenty individuals previously diagnosed with CVI (mean age=17 years 11months [SD 5 years 10months]; mean Verbal IQ=86.42 [SD 35.85]) and 30 individuals with neurotypical development (mean age=20 years 1month [SD 3 years 8months]; mean Verbal IQ=110.05 [SD 19.34]) participated in the study. In this two-group comparison, cross-sectional study design, global motion, and form pattern coherence thresholds were assessed using a computerized, generalizable, self-administrable, and response-adaptive psychophysical paradigm called FInD (Foraging Interactive D-prime). Results: Consistent with dorsal stream dysfunction, mean global motion (but not form) coherence thresholds were significantly higher in individuals with CVI compared to controls. No statistically significant association was found between coherence thresholds and lesion severity. Interpretation: These results suggest that the objective assessment of motion and form coherence threshold sensitivities using this psychophysical paradigm may be useful in helping to characterize perceptual deficits and the complex clinical profile of CVI.