Sack Alexander T, Kohler Axel, Bestmann Sven, Linden David E J, Dechent Peter, Goebel Rainer, Baudewig Juergen
Department of Cognitive Neuroscience, Faculty of Psychology, Maastricht University, 6200 MD Maastricht, The Netherlands.
Cereb Cortex. 2007 Dec;17(12):2841-52. doi: 10.1093/cercor/bhm013. Epub 2007 Mar 3.
Damage to parietal cortex impairs visuospatial judgments. However, it is currently unknown how this damage may affect or indeed be caused by functional changes in remote but interconnected brain regions. Here, we applied transcranial magnetic stimulation (TMS) to the parietal cortices during functional magnetic resonance imaging (fMRI) while participants were solving visuospatial tasks. This allowed us to observe both the behavioral and the neural effects of transient parietal activity disruption in the active healthy human brain. Our results show that right, but not left, parietal TMS impairs visuospatial judgment, induces neural activity changes in a specific right-hemispheric network of frontoparietal regions, and shows significant correlations between the induced behavioral impairment and neural activity changes in both the directly stimulated parietal and remote ipsilateral frontal brain regions. The revealed right-hemispheric neural network effect of parietal TMS represents the same brain areas that are functionally connected during the execution of visuospatial judgments. This corroborates the notion that visuospatial deficits following parietal damage are brought about by a perturbation of activity across a specific frontoparietal network, rather than the lesioned parietal site alone. Our experiments furthermore show how concurrent fMRI and magnetic brain stimulation during active task execution hold the potential to identify and visualize networks of brain areas that are functionally related to specific cognitive processes.
顶叶皮质受损会损害视觉空间判断能力。然而，目前尚不清楚这种损伤如何影响或实际上由远程但相互连接的脑区的功能变化所引起。在这里，我们在功能磁共振成像（fMRI）期间对参与者解决视觉空间任务时的顶叶皮质施加经颅磁刺激（TMS）。这使我们能够观察到活跃健康人脑中短暂顶叶活动中断的行为和神经效应。我们的结果表明，右侧而非左侧顶叶TMS会损害视觉空间判断，在特定的右侧额顶叶区域网络中诱导神经活动变化，并且在直接刺激的顶叶和同侧额叶脑区中，诱导的行为损伤与神经活动变化之间存在显著相关性。所揭示的顶叶TMS的右侧半球神经网络效应代表了在执行视觉空间判断时功能连接的相同脑区。这证实了这样一种观点，即顶叶损伤后的视觉空间缺陷是由特定额顶叶网络活动的扰动引起的，而不仅仅是受损的顶叶部位。我们的实验还表明，在执行主动任务期间同时进行fMRI和脑磁刺激有潜力识别和可视化与特定认知过程功能相关的脑区网络。
