O'Brien J M, Spencer J V, 2005, "Motion processing in dyslexia and Asperger syndrome: an fMRI study" Perception 34 ECVP Abstract Supplement
Motion processing in dyslexia and Asperger syndrome: an fMRI study
J M O'Brien, J V Spencer
Deficits in motion processing but not form processing have been reported in dyslexia. Deficits in both motion and form processing have been reported in autism, but the data are less equivocal for Asperger syndrome. To investigate the neural bases of these visual deficits we conducted an event-related fMRI study of form and motion processing on a group of adults with dyslexia, a group with Asperger syndrome, and a control group. The purpose of this study was to identify the loci of deficits in spatial integration and motion integration with the use of form-coherence and motion-coherence detection tasks. The stimuli consisted of Glass patterns comprising dot triplets separated by a rotational transformation in space to generate a static form-coherence pattern, or dots rotated over time to generate a coherent motion display. Fixed levels of stimulus coherence were used from 0.0 (all dot transformations in a random direction) to 1.0 (all dot transformations in the coherent direction). The Glass pattern was embedded in a field of random dots and a participant's task was to identify its location to either the left or right of the central fixation point. The order of events was permuted in a pseudo-random fashion. A number of areas have previously been identified as responding to motion coherence and to form coherence (Braddick et al, 2000 Current Biology 10 731 - 734), and these were used as the basis for a region-of-interest analysis. The BOLD response to form coherence did not differ significantly between experimental groups. The BOLD response to motion coherence was nonlinear in V5 for the dyslexia group, compared to the linear relationship for the Asperger syndrome and control groups.
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