動作制御機能の中枢

Cortical Areas for Controlling Voluntary Movements

一次運動野はブロードマン4野，前頭葉の最後部に位置しており，運動指令を脳幹や脊髄に出力している。ブロードマン4野の前方には6野があり，複数の高次運動野が同定されている。外側面には運動前野が位置し，感覚情報に基づいた動作の企画や実行に関与する。内側面には補足運動野があり，内的情報に基づく動作の企画や実行に関与する。4野と6野は，動作のアイデアを具体的な運動に変換する中枢であると考えられる。

Abstract

The primary motor cortex is located in Brodmann area 4 at the most posterior part of the frontal lobe. The primary motor cortex corresponds to an output stage of motor signals, sending motor commands to the brain stem and spinal cord. Brodmann area 6 is rostral to Brodmann area 4, where multiple higher-order motor areas are located. The premotor area, which is located in the lateral part, is involved in planning and executing action based on sensory signals. The premotor area contributes to the reaching for and grasping of an object to achieve a behavioral goal. The supplementary motor area, which occupies the mesial aspect, is involved in planning and executing actions based on internalized or memorized signals. The supplementary motor area plays a central role in bimanual movements, organizing multiple movements, and switching from a routine to a controlled behavior. Thus, Brodmann areas 4 and 6 are considered as central motor areas in the cerebral cortex, in which the idea of an action is transformed to an actual movement in a variety of contexts.