Department of Physiology, Graduate School of Medicine, Nagoya University, 65 Tsurumai-cho, Showa-ku, Nagoya, Japan.
Neuroimage. 2010 Jan 1;49(1):1108-15. doi: 10.1016/j.neuroimage.2009.07.034. Epub 2009 Jul 24.
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 visuospatial information, referred to here as "visuospatial mental operation". However, the functions assigned to the PMd and PPC during these tasks are still unclear. Here, 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 was applied at different times in relation to the visuospatial mental operation cue. Consequently, only the TMS applied at 300 ms after the cue affected the task performance. Furthermore, we found that the TMS at this time to each area differentially affected the performance: 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 operations.
人类神经影像学研究经常报告在内部操作视空间信息期间背侧运动前皮质 (PMd) 和后顶叶皮质 (PPC) 的共同激活，这里称为“视空间心理操作”。然而，在这些任务中分配给 PMd 和 PPC 的功能仍不清楚。在这里，我们使用经颅磁刺激 (TMS) 技术检查了这两个区域对视空间心理操作的重要性。受试者执行了一项需要视空间心理操作的任务。在 TMS 实验之前使用功能磁共振成像 (fMRI) 进行的定位研究表明，PMd 和顶叶内侧部分、楔前叶 (PCu) 在视空间心理操作期间特异性激活。然后，我们使用双脉冲 TMS 在相同的任务中干扰右半球的 PMd 和 PCu 的活动，以确定这些活动是否对任务是必需的。TMS 施加的时间与视空间心理操作提示有关。结果，只有在提示后 300 毫秒施加的 TMS 会影响任务性能。此外，我们发现此时对每个区域的 TMS 会以不同的方式影响性能：PMd 的 TMS 会阻碍任务的执行，而 PCu 的 TMS 则会促进任务的执行，而不会牺牲速度/准确性。在没有视空间心理操作的对照条件下没有发现这些影响。这些发现表明 PMd 和 PCu 参与了视空间心理操作的不同方面。
