Schluter N D, Rushworth M F, Mills K R, Passingham R E
Department of Experimental Psychology, University of Oxford, UK.
Neuropsychologia. 1999 Feb;37(2):233-43. doi: 10.1016/s0028-3932(98)00098-0.
Single unit recording studies in non-human premotor cortex have revealed neurons with motor-related activity. Other neurons, however, seem to be involved in prior movement selection and preparation processes, and have activity related to visual instruction signals or movement preparation ('set'). We have used single pulse transcranial magnetic stimulation (TMS) to identify similar processes in human subjects. In Experiment 1 subjects performed a cued movement task while being stimulated with TMS over three sites: sensorimotor cortex, posterior premotor cortex and anterior premotor cortex. TMS slowed movements when applied at 140 ms after the visual cue over the anterior premotor site, at 180 ms after the visual cue over the posterior premotor site, and at 220 ms and later after the visual cue over the sensorimotor cortex. The results are consistent with a change from signal to movement-related processing when moving from premotor to motor cortex. In Experiment 2 there was a preparatory set period between the instruction signal that informed subjects which movement to make and the 'go' signal that informed them when to actually make the movement. TMS was applied over the anterior premotor site and the sensorimotor site during the set period. At both sites TMS had similar effects on slowing subsequent movements. The results suggest set activity in both premotor and motor cortices in human subjects.
在非人类运动前区皮质进行的单神经元记录研究发现了具有运动相关活动的神经元。然而，其他神经元似乎参与了先前的运动选择和准备过程，并且具有与视觉指令信号或运动准备（“定势”）相关的活动。我们使用单脉冲经颅磁刺激（TMS）来识别人类受试者中的类似过程。在实验1中，受试者执行一个线索化运动任务，同时在三个部位接受TMS刺激：感觉运动皮质、后运动前区皮质和前运动前区皮质。当在视觉线索出现后140毫秒在前运动前区部位施加TMS、在视觉线索出现后180毫秒在后运动前区部位施加TMS以及在视觉线索出现后220毫秒及更晚在感觉运动皮质部位施加TMS时，运动速度减慢。这些结果与从运动前区皮质向运动皮质移动时从信号处理转变为运动相关处理一致。在实验2中，在告知受试者要进行何种运动的指令信号和告知他们何时实际进行运动的“开始”信号之间有一个准备定势期。在定势期内，在前运动前区部位和感觉运动皮质部位施加TMS。在这两个部位，TMS对减慢后续运动有类似的影响。结果表明人类受试者的运动前区皮质和运动皮质中都存在定势活动。
