BRAIN and NERVE－神経研究の進歩61巻12号

2009年12月発行

特集 Somatotopy再考

大脳基底核のsomatotopy

著者： 南部篤¹

所属機関： ¹自然科学研究機構生理学研究所生体システム研究部門

ページ範囲：P.1383 - P.1394

文献概要

はじめに

　身体の各部位と脳の領域が対応しているというsomatotopyは，脳機能研究において基本的かつ重要な概念である。各領域のsomatotopyを調べることは，機能を調べる手がかりとなると同時に，実際の実験において必須の知識である。また，疾患時においてsomatotopyが変化することも報告されている。本稿では大脳基底核のsomatotopyを紹介することを通して，大脳基底核の機能について考えてみたい。研究が進んでいるサルを中心に述べるが，ヒトの所見とは矛盾しないので，ヒトでも同様と考えられる。

　感覚野では，例えば視覚野に代表されるように，一次野から高次領野に至るにしたがって情報処理が進み，受容野が大きくなる一方で，色，形などほかの神経情報がコードされるようになる。しかし，運動皮質では，それぞれ特徴的な活動はあるものの，高次領野でも基本的なsomatotopyが保たれている。この意味するところは，抽象的な運動というものが存在し，それらが順に関節や筋肉の運動にデコードされ実際の運動が起こる訳ではないということであろう。以下に述べるように，大脳基底核を構成する核においても，それぞれsomatotopyが存在するので，大脳基底核の回路の中で身体各部位の情報は独立して処理されていると考えられる。

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