Shmuelof Lior, Zohary Ehud
Department of Neurobiology, Hebrew University, Jerusalem, Israel 91904.
J Neurosci. 2006 Sep 20;26(38):9736-42. doi: 10.1523/JNEUROSCI.1836-06.2006.
The anterior part of the human intraparietal sulcus is known to be involved in visually guided grasping. This region is also active during the observation of object manipulation by others. Here, we explore the nature of action representation using functional magnetic resonance imaging (fMRI). Fourteen subjects observed video clips showing object manipulation by the right or left hand. The clips were presented in either the right or left peripheral visual field. The fMRI activation in the occipital cortex and in the caudal sections of the parietal cortex was specific to the visual-field location of the clips. In contrast, the principal factor determining the response in anterior intraparietal cortex was the identity of the observed hand. Furthermore, these "hand-specific" parietal areas also showed contralateral hand specificity during self action (i.e., object manipulation) without visual feedback. A similar selectivity for the identity of the observed hand was seen when using a region of interest analysis, focusing on individually defined visuomotor voxels within the parietal cortex. This dual visuomotor grasping representation lends further evidence for the existence of a mirror system in humans and suggests that the anterior intraparietal cortex is involved in the specific motor simulation of hand actions.
已知人类顶内沟前部与视觉引导的抓握动作有关。在观察他人进行物体操作时，该区域也会活跃起来。在此，我们使用功能磁共振成像（fMRI）来探究动作表征的本质。14名受试者观看了展示右手或左手进行物体操作的视频片段。这些片段分别出现在右侧或左侧外周视野中。枕叶皮层和顶叶皮层尾段的fMRI激活情况与视频片段的视野位置有关。相反，决定顶内沟前部反应的主要因素是所观察手的身份。此外，这些“手特异性”顶叶区域在无视觉反馈的自身动作（即物体操作）过程中也表现出对侧手的特异性。当使用感兴趣区域分析，聚焦于顶叶皮层内个体定义的视觉运动体素时，也能看到对所观察手的身份有类似的选择性。这种双重视觉运动抓握表征为人类镜像系统的存在提供了进一步证据，并表明顶内沟前部参与了手部动作的特定运动模拟。
