Parieto-frontal connectivity during visually guided grasping.
Parieto-frontal connectivity during visually guided grasping.
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DOI：
10.1523/jneurosci.3923-07.2007
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发表时间：
2007-10-31
期刊：
影响因子：
--
通讯作者：
Toni I
中科院分区：
文献类型：
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作者：
Grol MJ;Majdandzić J;Stephan KE;Verhagen L;Dijkerman HC;Bekkering H;Verstraten FA;Toni I
抓取物体需要处理关于物体的外在特征（空间位置）和内在特征（大小，形状，方向）的视觉空间信息。因此，手动抓握已经被细分为到达组件和抓握组件，到达组件基于物体的外在特征朝向物体引导手，抓握组件基于物体的内在特征围绕物体的质心预成形手指。在神经方面，这种区别已被链接到一个专门的背内侧“达到”电路和背外侧“抓”电路，处理外在和内在的功能，通过顶叶区与背侧和腹侧运动前皮质，分别连接枕区。我们已经测试了另一种可能性，即两个电路的相对贡献与电子运动所需的在线控制程度有关。我们使用fMRI时间序列的动态因果模型来评估顶叶-额叶连接是如何通过对不同大小和宽度的物体进行规划和执行扩展运动来调节的。这种实验性的操作引起了不同的运动，对不同的对象有不同的计划和执行阶段。至关重要的是，抓住大的物体增加了背内侧回路内的区域间耦合，而抓住小的物体增加了主要背外侧回路的有效连接，这些回路之间有一定程度的重叠。这些结果反对专门的大脑回路的存在达到和把握，这表明背外侧和背内侧电路的贡献是一个功能的运动所需的在线控制的程度。
Grasping an object requires processing visuospatial information about the extrinsic features (spatial location) and intrinsic features (size, shape, orientation) of the object. Accordingly, manual prehension has been subdivided into a reach component, guiding the hand towards the object on the basis of its extrinsic features, and a grasp component, pre-shaping the fingers around the center of mass of the object on the basis of its intrinsic features. In neural terms, this distinction has been linked to a dedicated dorsomedial ‘reaching’ circuit and a dorsolateral ‘grasping’ circuit that process extrinsic and intrinsic features, linking occipital areas via parietal regions with the dorsal and ventral premotor cortex, respectively. We have tested an alternative possibility, namely that the relative contribution of the two circuits is related to the degree of online control required by the prehension movement. We used Dynamic Causal Modelling of fMRI-timeseries to assess how parieto-frontal connectivity is modulated by planning and executing prehension movements towards objects of different size and width. This experimental manipulation evoked different movements, with different planning and execution phases for the different objects. Crucially, grasping large objects increased inter-regional couplings within the dorsomedial circuit, whereas grasping small objects increased the effective connectivity of a mainly dorsolateral circuit, with a degree of overlap between these circuits. These results argue against the presence of dedicated cerebral circuits for reaching and grasping, suggesting that the contributions of the dorsolateral and the dorsomedial circuits are a function of the degree of on-line control required by the movement.