Clavagnier Simon, Prado Jérôme, Kennedy Henry, Perenin Marie-Thérèse
Laboratorium voor Neuroen Psychofysiologie, Medical School, K.U. Leuven, Belgium.
Neuroscientist. 2007 Feb;13(1):22-7. doi: 10.1177/1073858406295688.
Lesions of the posterior parietal cortex in humans can produce a specific disruption of visually guided hand movements termed optic ataxia. The fact that the deficit mainly occurs in peripheral vision suggests that reaching in foveal and extrafoveal vision relies on two different anatomical substrates. Using fMRI in healthy subjects, the authors demonstrated the existence of two systems, differently modulated by the two reaching conditions. Reaching in central vision involves a restricted network, including the medial intraparietal sulcus (mIPS) and the caudal part of the dorsal premotor cortex (PMd). Reaching in peripheral vision engages a more extensive network, including the parieto-occipital junction (POJ). Interestingly, POJ corresponds to the site of the lesion overlap that the authors recently found to be responsible for optic ataxia. These two sets of results converge to show that there is not a unique cortical network for reaching control but instead two systems engaged in reaching to targets in the central and peripheral visual field.
人类顶叶后皮质的损伤会导致一种特定的视觉引导手部运动障碍，称为视觉性共济失调。这种缺陷主要发生在周边视觉中的事实表明，在中央凹和中央凹外视觉中的伸手动作依赖于两种不同的解剖学基质。作者通过对健康受试者进行功能磁共振成像（fMRI），证明了存在两个系统，它们在两种伸手条件下受到不同的调节。在中央视觉中伸手涉及一个受限的网络，包括内侧顶内沟（mIPS）和背侧运动前皮质（PMd）的尾部。在周边视觉中伸手则涉及一个更广泛的网络，包括顶枕交界区（POJ）。有趣的是，POJ对应于作者最近发现的与视觉性共济失调有关的病变重叠部位。这两组结果共同表明，不存在用于控制伸手动作的单一皮质网络，而是有两个系统参与在中央和周边视野中伸向目标的动作。
