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Mu rhythm, one of the EEG alpha components, is recorded at the central region on the scalp corresponding to the sensorimotor area, and is reduced by activation of the brain motor system. It has been reported that high-functioning individuals with autism spectrum disorders(ASD) show mu power suppression related to self-performed hand movements but not when observing those performed by others. To clarify whether these phenomena were specific to high-functioning individuals with ASD, we measured mu power for observing and executing movements in 14 non-ASD and 11 ASD children (the age ranged from 6 to 18 years old) with intellectual disabilities. EEG rhythms were recorded on the scalp while subjects were resting with eyes open; watching animated clips of ball throw, ball catch, paper rock (i.e., opening and closing of fist) and bouncing ball; moving their own hand to catch a ball and do paper rock.We focused on the alpha component at the central region contralateral to the dominant hand. In the non-ASD group, alpha power was distinctly suppressed when subjects observed other's paper rock and performed their own, compared with rest and other conditions. We consider that this alpha component was mu rhythm and the power suppression indicated activation of the brain system for simple motor tasks than for complex tasks such as ball handling. Mu suppression for simple actual and observed tasks such as paper rock were less in the ASD group than in the non-ASD group. We suggest that this weak activation of observation and execution system for movement is characteristic of individuals with both ASD and intellectual disabilities but not of non-ASD ones with intellectual disabilities. Furthermore, since there was a little mu suppression for simple tasks in children with ASD, we should investigate a required condition to activate the brain motor system for children with ASD.
研究論文集－教育系・文系の九州地区国立大学間連携論文集－ 5(2), 2012-03-00