Bestmann S, Thilo K V, Sauner D, Siebner H R, Rothwell J C
Sobell Department of Motor Neuroscience and Movement Disorders, Institute of Neurology, University College of London, Queen Square, WC1N 3BG, United Kingdom.
Neuroimage. 2002 Nov;17(3):1512-20. doi: 10.1006/nimg.2002.1266.
Visuomotor rotation (VMR) is a variant of the classic mental rotation paradigm. Subjects perform a center-out arm reaching movement, with the instruction to point clockwise or anticlockwise away from the direction of a reaction signal by a prespecified amount. Like classic mental rotation (MR) tasks, there is a linear relationship between reaction time (RT) and required angle of rotation (angular disparity). Although functional imaging studies have consistently demonstrated parietal activations centered around the intraparietal sulcus during MR tasks, the involvement of parietal cortex in VMR has not been investigated. The aim of the present experiments was to test in human subjects whether VMR also involves activity in parietal areas. We used short trains of transcranial magnetic stimulation (TMS) to produce a temporary "virtual lesion" of the posterior parietal cortex (PPC) around the intraparietal sulcus during the reaction period of a VMR task. Four pulses of 20-Hz rTMS were applied to the left PPC, right PPC, or vertex (control condition) 100 ms after the presentation of an instruction cue. Reaction times (RTs) were evenly prolonged by right or left parietal TMS compared with vertex stimulation, but only for large angles of rotation, and without affecting the spatial accuracy of the final response. A control experiment showed that parietal rTMS did not impair visual perception or the ability to judge the size of visual angles. The data thus provide evidence for bilateral involvement of the PPC in VMR that increases with processing demands.
视觉运动旋转（VMR）是经典心理旋转范式的一种变体。受试者进行从中心向外的手臂伸展运动，并按照指示以预先指定的量顺时针或逆时针指向远离反应信号方向的位置。与经典心理旋转（MR）任务一样，反应时间（RT）与所需旋转角度（角度差异）之间存在线性关系。尽管功能成像研究一致表明在MR任务期间顶叶激活集中在顶内沟周围，但尚未研究顶叶皮质在VMR中的参与情况。本实验的目的是在人类受试者中测试VMR是否也涉及顶叶区域的活动。我们在VMR任务的反应期使用短串经颅磁刺激（TMS）在顶内沟周围的后顶叶皮质（PPC）产生临时的“虚拟损伤”。在呈现指令提示后100毫秒，将20赫兹重复经颅磁刺激的四个脉冲施加到左侧PPC、右侧PPC或头顶（对照条件）。与头顶刺激相比，右侧或左侧顶叶TMS使反应时间（RTs）均匀延长，但仅在旋转角度较大时出现，且不影响最终反应的空间准确性。一项对照实验表明，顶叶rTMS不会损害视觉感知或判断视角大小的能力。因此，数据为PPC在VMR中的双侧参与提供了证据，这种参与随着处理需求的增加而增加。
