| 研究概要 |
運動と認知の共通制御神経機構である前頭葉の高次運動皮質と頭頂葉の楔前部の機能分担を検討した。前頭葉高次運動皮質の活動を干渉した場合は、反応時間が延長し正答率も悪化するのに対して、頭頂葉楔前部の活動を干渉した場合は、反応時間が統計的有意に短縮するだけでなく正答率はむしろ改善する傾向を示した。これらの結果は、前頭葉高次運動皮質は認知的操作をフィードフォワード制御し、頭頂葉皮質は認知的制御のフォードバックモニタリングに関連することを示唆する。
Human neuro-imaging studies have often reported co-activation of the dorsal premotor cortex (PMd) and the posterior parietal cortex (PPC) during internal operation of imagined visuospatial information, reffered to, here, as "visuospatial mental operation". We examined the significance of these two areas for a visuospatial mental operation using the transcranial magnetic stimulation (TMS) technique. Subjects performed a task in which a visuospatial mental operation was required. A localization study conducted prior to the TMS experiment using functional magnetic resonance imaging (fMRI) revealed that the PMd and the medial part of the PPC, precuneus (PCu), were specifically activated during the visuospatial mental operation. Then, we impeded the activities of the PMd and the PCu in the right hemisphere during the same task using double-pulse TMS to determine whether these activities were necessary for the task. The TMS to the PMd hindered the performance of the task whereas TMS to the PCu facilitated it without a speed/accuracy trade-off. These effects were not found in the control condition that lacked a visuospatial mental operation. These findings suggest that the PMd and the PCu are involved in differential aspects of visuospatial mental operation.
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