Electrophysiological Assessment of Visual Function in Autism Spectrum Disorders
The human visual system is characterized by a set of parallel, hierarchical multistage systems that are specialized
to process different types of visual stimuli. There are two major parallel streams: the parvocellular (or ventral) and
magnocellular (or dorsal) pathways. The former projects to the inferior temporal cortex for object and color vision,
whereas the latter connects to the parietal cortex for motion and spatial vision. Individuals with autism spectrum disorder
(ASD) often show inferior global motion perception but superior performance in detailed form (local structure) perception.
These unique behaviors suggest the possibility of an impairment of the parallel visual pathways in ASD. Visual
evoked potentials (VEPs) and event-related potentials (ERPs) are non-invasive electrophysiological methods that provide
objective information about the function of the visual system. We have recently developed VEPs and ERPs with visual
stimuli designed to preferentially stimulate the different levels of each visual pathway. In this review, we introduce the
application of VEP and ERP techniques for the assessment of visual perception in ASD. Current data indicate that the
atypical visual perception observed in ASD may be caused by the dysfunction of complicated brain networks within the
parallel visual pathways, and may contribute to the impaired social communication involved in ASD. Therefore, we conclude
that electrophysiological techniques are useful for understanding the pathophysiology of ASD.
Keywords: Autism spectrum disorder, event-related potential, parallel visual pathway, visual evoked potential.
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