Functional imbalance of visual pathways indicates alternative face processing strategies in autism

Objective: To investigate whether autistic subjects show a different pattern of neural activity than healthy individuals during processing of faces and complex patterns. Methods: Blood oxygen level-dependent (BOLD) signal changes accompanying visual processing of faces and complex patterns were analyzed in an autistic group (n=7; 25.3 [6.9] years) and a control group (n=7; 27.7 [7.8] years). Results: Compared with unaffected subjects, autistic subjects demonstrated lower BOLD signals in the fusiform gyrus, most prominently during face processing, and higher signals in the more object-related medial occipital gyrus. Further signal increases in autistic subjects vs controls were found in regions highly important for visual search: the superior parietal lobule and the medial frontal gyrus, where the frontal eye fields are located. Conclusions: The cortical activation pattern during face processing indicates deficits in the face-specific regions, with higher activations in regions involved in visual search. These findings reflect different strategies for visual processing, supporting models that propose a predisposition to local rather than global modes of information processing in autism.