Autism has been associated with enhanced local processing on visual tasks. Originally, this was based on findings that individuals
with autism exhibited peak performance on the block design test (BDT) from the Wechsler Intelligence Scales. In autism, the
neurofunctional correlates of local bias on this test have not yet been established, although there is evidence of alterations
in the early visual cortex. Functional MRI was used to analyze hemodynamic responses in the striate and extrastriate visual
cortex during BDT performance and a color counting control task in subjects with autism compared to healthy controls. In autism,
BDT processing was accompanied by low blood oxygenation level-dependent signal changes in the right ventral quadrant of V2.
Findings indicate that, in autism, locally oriented processing of the BDT is associated with altered responses of angle and
grating-selective neurons, that contribute to shape representation, figure-ground, and gestalt organization. The findings
favor a low-level explanation of BDT performance in autism.
Keywords: Pervasive developmental disorders; brain; neurobiology, fMRI; visual processing; weak central coherence; neuropsychology
Correspondence: Sven Bölte, Klinik für Psychiatrie und Psychotherapie des Kindes- und Jugendalters, Deutschordenstr. 50, 60528
Frankfurt/Main, Germany