幼児用MEGによる未就学広汎性発達障害児の生理学的検討

金沢大学子どものこころの発達研究センターAutism spectrum disorders (ASD) appear in infancy and early childhood, causing delays or impairments in social interaction, communication, and a restricted range of interests. With recent developments in neuroimaging methods, the accumulated evidence suggests that aberrant brain connectivity reflect important aspects of network dysfunction associated with the pathophysiology of ASD. To gain insight into the development of this network dysfunction, it is necessary to study the pathophysiology in younger children with ASD, as aberrant development of white matter pathways may appear in infant stage. However, under conscious conditions, it has been challenging to measure brain functional connectivity in young children with ASD children using creditable methods as they are not always cooperative and persevering. We have recently reported the aberrant brain functional connectivity under conscious conditions in pre- school children with ASD. In our recent studies, we developed the child custom- sized MEG system in which sensors are as close to the whole head as possible for optimal recording even in young children, which otherwise would have been difficult with a conventional adult- sized MEG system. This is a unique and useful technique for young children that can provide measures of cortical neural activity on a millisecond timescale. By obtaining non- invasive measurements with a child custom- sized MEG, we have demonstrate an aberrant brain functional lateralization in conscious preschool children with ASD.最近の脳画像研究により，広汎性発達障害において，脳の側性化が定型発達者に比して乏しいことが報告されている。これらの所見は，脳の構造画像，脳血流の反応などにより報告されてきた。しかし，就学前の広汎性発達障害児童の覚醒状態脳機能の側性化については，これまでほとんど検討されていない。近年我々は，未就学の広汎性発達障害児と，定型発達児を対象に幼児用脳磁計（MEG）をもちいた脳機能測定を進めてきた。その結果，広汎性発達障害に特徴的ないくつかの所見が得られつつある。今回用いた幼児用MEGにおいては，従来の成人用MEGを幼児に行う場合に困難であった左右半球の脳機能測定を容易に行うことが可能となった。磁場の物理的性質から，半球間の機能の比較などを評価する点において，脳波に比べて妥当な方法で，さらに，MEGは電極の装着などの煩雑さがなく，母親の傍らで簡便に行うことが可能である点で，幼児には理想的な方法である