Laboratory of Clinical and Behavioural Neurology, Santa Lucia Foundation IRCCS, Via Ardeatina 306, 00179 Rome, Italy.
Neuroimage. 2010 May 15;51(1):300-12. doi: 10.1016/j.neuroimage.2010.02.022. Epub 2010 Feb 13.
We combined bifocal transcranial magnetic stimulation (TMS) and diffusion tensor imaging (DTI) tractography to investigate in humans the contribution of connections originating from different parietal areas in planning of different reaching to grasp movements. TMS experiments revealed that in the left hemisphere functional connectivity between the primary motor cortex (M1) and a portion of the angular gyrus (AG) close to the caudal intraparietal sulcus was activated during early preparation of reaching and grasping movements only when the movement was made with a whole hand grasp (WHG) towards objects in contralateral space. In contrast, a different pathway, linking M1 with a part of the supramarginal gyrus (SMG) close to the anterior intraparietal sulcus, was sensitive only to the type of grasp required (precision grasping) but not to the position of the object in space. A triple coil experiment revealed that inactivation of the ventral premotor area (PMv) by continuous theta burst stimulation interfered with some of these interactions. Anatomical DTI tractography revealed that AG and SMG are strongly connected with PMv and with M1 by different bundles of the superior longitudinal fasciculus (SLF). These results demonstrate the existence of segregated parieto-premotor-motor pathways crucial for preparation of different grasping actions and indicate that these may process information relevant to both the position of the object and the hand shape required to use it.
我们结合双焦点经颅磁刺激（TMS）和弥散张量成像（DTI）束追踪技术，在人类中研究了源自不同顶叶区域的连接在不同伸手抓握运动规划中的贡献。TMS 实验表明，在左半球，初级运动皮层（M1）与靠近顶内沟后部的角回（AG）的一部分之间的功能连接仅在进行全手握持（WHG）伸向对侧空间中的物体时，在伸手抓握运动的早期准备中被激活。相比之下，另一条连接 M1 与靠近顶内沟前部的缘上回（SMG）一部分的通路仅对所需的抓握类型（精确抓握）敏感，而不对物体在空间中的位置敏感。一项三线圈实验表明，连续 theta 爆发刺激对腹侧运动前区（PMv）的失活会干扰其中的一些相互作用。解剖学 DTI 束追踪显示，AG 和 SMG 与 PMv 和 M1 通过上纵束（SLF）的不同束强烈连接。这些结果表明，存在分离的顶-运动前-运动通路对于不同抓握动作的准备至关重要，并表明这些通路可能处理与物体位置和使用它所需的手形相关的信息。
