Neural Correlates of Phonological Processing in Autism: A MEG Investigation. (funded through NAAR)

Individuals with autism may have abnormal development of expressive speech and impairments in auditory and speech perceptual processing. Little is known about cortical mechanisms underlying impaired language development in autism. This study used magnetoencephalography (MEG) to non-invasively measure neural activity in auditory cortical sites in individuals with autism. This technique allowed researchers to track neuronal activity with sub-millisecond temporal resolution. Previous work had provided evidence that early sensory processing of simple and complex sounds appears to be intact in individuals with autism. However, the pervasive nature of language deficits in autism indicates that linguistically relevant sound processing may nonetheless be impaired in this population. The researchers hypothesized that while early processing of acoustic signal appears normal in individuals with autism, later phonological processes that provide feature extraction, discrimination, and categorization necessary for decoding the speech signal may be disrupted. They measured later stages of neural activity, including correlates of phonological processing with the aim of providing quantitative measures to assess the nature and cortical timing of language related sound processing abnormalities in autism.