| Popis: |
Impairment in communication is a core symptom of autism. Research has shown most typically developing right handed individuals display left hemisphere lateralization in language areas of the brain. Neuroanatomical research in autism has shown a reversal of left hemisphere cortical brain volume asymmetry in several language areas of the brain, including inferior frontal gryus and superior temporal gyrus. Functional neuroimaging research in autism has also shown atypical right hemisphere recruitment during language comprehension. Research using electroencephalography (EEG) alpha band spectral power analysis has also shown atypical lateralization in adolescents and adults with autism during verbal tasks. Here we examined brain oscillations, measured with EEG, during a verbal labeling experiment and a passive listening experiment to examine hemispheric activity during language processing in children aged 4 – 6 years old with autism spectrum disorder versus typically developing controls. Our research is the first we know of using spectral power analysis to examine early language lateralization in children with autism spectrum disorder. Our results show no difference for lateralization of language, using alpha power as an indicator, between the children with autism spectrum disorder and the control group for language production or language comprehension. A leftward lateralization index in the T5 – T6 regions for the gamma band (30 – 70Hz.), and increased alpha (8 – 12Hz) activity in the F7 region, during language production tasks was found. Increased beta activity in the F7 region was also detected during the language comprehension tasks. Gamma activity in the F7 and F8 regions was also found to negatively correlate with both language production and language comprehension performance. High gamma activity may reflect poor signal-to-noise ratio neural processing, while increased alpha and beta activity may reflect decreased cortical activation and increased neural inhibitory processing respectively, during language processing in children with autism spectrum disorder. In addition to EEG, we also explored the technical feasibility of using functional near infrared spectroscopy (fNIRS) for noninvasive detection of language lateralization in children with autism spectrum disorder. Our pilot trials imply the clinical feasibility of using EEG for assessment of language lateralization, whereas further technology development and validation works are required before fNIRS can be used to detect language lateralization in children with autism spectrum disorder. |
