Summary.  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. Content Type Journal ArticleDOI 10.1007/s00702-007-0850-1Authors S. Bölte, J. W. Goethe-University Department of Child and Adolescent Psychiatry Frankfurt/Main GermanyD. Hubl, University Hospital of Clinical Psychiatry Department of Psychiatric Neurophysiology Bern SwitzerlandT. Dierks, University Hospital of Clinical Psychiatry Department of Psychiatric Neurophysiology Bern SwitzerlandM. Holtmann, J. W. Goethe-University Department of Child and Adolescent Psychiatry Frankfurt/Main GermanyF. Poustka, J. W. Goethe-University Department of Child and Adolescent Psychiatry Frankfurt/Main Germany Journal Journal of Neural TransmissionOnline ISSN 1435-1463Print ISSN 0300-9564 (Source: Journal of Neural Transmission)


Original source here