Cerebral correlates of preserved cognitive skills in autism - A functionalMRI study of Embedded Figures Task performance

When considering the cognitive abilities of people with autism, the majorit y of studies have explored domains in which there are deficits. However, on tests of local processing and visual search, exemplified by the Embedded F igures Task (EFT), people with autism have been reported to demonstrate sup eriority over normal controls. This study employed functional MRI of subjec ts during the performance of the EFT to test the hypothesis that normal sub jects and a group with autism would activate different brain regions and th at differences in the patterns of these regional activations would support distinct models of cerebral processing underlying EFT performance in the tw o groups. It was found that several cerebral regions were similarly activat ed in the two groups, However, normal controls, as well as demonstrating ge nerally more extensive task-related activations, additionally activated pre frontal cortical areas that were not recruited in the group with autism. Co nversely, subjects with autism demonstrated greater activation of ventral o ccipitotemporal regions. These differences in functional anatomy suggest th at the cognitive strategies adopted by the two groups are different: the no rmal strategy invokes a greater contribution from working memory systems wh ile the autistic group strategy depends to an abnormally large extent on vi sual systems for object feature analysis. This interpretation is discussed in relation to a model of autism which proposes a predisposition towards lo cal rather than global modes of information processing.