Dafotakis Manuel, Sparing Roland, Eickhoff Simon B, Fink Gereon R, Nowak Dennis A
Institute of Neuroscience and Biophysics , Research Centre Jülich, Jülich, Germany.
Brain Res. 2008 Sep 4;1228:73-80. doi: 10.1016/j.brainres.2008.06.027. Epub 2008 Jun 19.
When lifting objects of different mass but identical visual appearance, we apply grip forces that match the expected mass of the object. Here we study the role of the primary motor cortex (M1), the ventral premotor cortex (PMv) and the anterior intraparietal area (AIP) for predictive and reactive scaling of grip forces. Participants performed a precision grip between the index finger and thumb of the right hand to lift two different masses of identical visual appearance in random order. Neuronavigated single pulse transcranial magnetic stimulation (TMS) over (i) left M1, (ii) left PMv, (iii) left AIP and (iv) the vertex (for control) was applied at two time points of the grasping movement after an unexpected change in mass had occurred: (a) at the time of movement onset and (b) at the time of peak grasp aperture. TMS over the PMv, but not over the vertex, M1 or the AIP, interfered with the predictive scaling of grip forces according to the most recent lift when applied at the time of peak grasp aperture. In contrast, TMS over AIP, but not over the vertex, M1 or PMv, disrupted the reactive adjustment of grip force to the novel mass of the object at hand. The findings highlight the differential involvement of PMv in the predictive scaling of grip force and of AIP in the reactive online adjustment of grip force during object manipulation.
当提起质量不同但视觉外观相同的物体时，我们施加的握力与物体的预期质量相匹配。在此，我们研究初级运动皮层（M1）、腹侧运动前皮层（PMv）和顶内前区（AIP）在握力预测性和反应性缩放中的作用。参与者用右手食指和拇指进行精确抓握，以随机顺序提起两个视觉外观相同但质量不同的物体。在质量意外变化后的抓握运动的两个时间点，对（i）左侧M1、（ii）左侧PMv、（iii）左侧AIP和（iv）头顶（作为对照）进行神经导航单脉冲经颅磁刺激（TMS）：（a）在运动开始时，以及（b）在抓握孔径峰值时。在抓握孔径峰值时施加TMS，刺激PMv而非头顶、M1或AIP，会干扰根据最近一次提起情况对握力进行的预测性缩放。相反，刺激AIP而非头顶、M1或PMv，会破坏对手中物体新质量的握力反应性调整。这些发现突出了PMv在物体操作过程中握力预测性缩放以及AIP在握力反应性在线调整中的不同参与情况。
