Cortical mechanisms underlying visual motion processing impairments in autism
Autism is typically recognized by disturbed social, communicative and imaginative functions. Sensory and cognitive processing, however, may also be altered and play an important role in the pathophysiology of this neurodevelopmental disorder. One emerging hypothesis is that autism is a neural disorder involving a widely distributed brain network, as opposed to a single, specific brain lesion. Although it can explain the diversity of autistic features, this brain network hypothesis remains to be tested at a neural systems level. This project will study brain processing of global and local motion signals in autism. Global motion processing requires spatiotemporal integration over a network of neural components whereas local motion processing does not. Using a psychophysical approach, Dr. Chen and colleagues will examine global and local motion perception in autism patients (n=30), and in age- and sex-matched normal controls (n=30). The investigators will measure perceptual thresholds in the detection of the directions of global and local motion. Using an fMRI approach, they will examine the pattern of cortical activations while autism patients (n=10) and controls (n=10) perform the global and the local motion tasks. The level of fMRI BOLD signal changes in both sensory (extrastriate) and cognitive (prefrontal) cortices will be measured. This study will generate empirical data on whether and how global motion perception, a sensory process that provides critical visual signals for cognitive and social functioning, is altered in autism. What this means for people with autism: Ultimately, research on selected sensory and cognitive processes will lead to the identification of pathophysiological factors underlying autism, upon which targeted and effective intervention can be developed.