Fink Gereon R, Marshall John C, Weiss Peter H, Stephan Thomas, Grefkes Christian, Shah Nadim J, Zilles Karl, Dieterich Marianne
Institute of Medicine, Research Centre Jülich, Jülich, Germany.
Neuroimage. 2003 Nov;20(3):1505-17. doi: 10.1016/j.neuroimage.2003.07.006.
The temporary improvement of visuospatial neglect during galvanic vestibular stimulation (Scand. J. Rehabil. Med. 31 (1999)117) may result from correction of the spatial reference frame distorted by the responsible lesion. Prior to an investigation of the neural basis of this effect in neurological patients, exploration of the neural mechanisms underlying such procedures in normals is required to provide insight into the physiological basis thereof. Despite their clinical impact, the neural mechanisms underlying the interaction of galvanic (and other) vestibular manipulations with visuospatial processing (and indeed the neural bases of how spatial reference frames are computed in man) remain to be clarified. We accordingly used fMRI in normal volunteers to investigate the effect of galvanically induced interference with the egocentric spatial reference frame on the neural processes underlying allocentric visuospatial (line bisection) judgments. A significant specific interaction of galvanic vestibular stimulation with the neural mechanisms underlying allocentric visuospatial judgments was observed in right posterior parietal and ventral premotor cortex only. Activation of these areas previously found to be damaged in visuospatial neglect suggests that these effects reflect the increased processing demands when compensating for the distorted egocentric spatial reference frame while maintaining accurate performance during the allocentric spatial task. These results thus implicate right posterior parietal and right ventral premotor cortex in the computation of spatial reference frames. Furthermore, our data imply a specific physiological basis for the temporary improvement of visuospatial neglect in patients with right hemisphere lesions during galvanic vestibular stimulation and may thus impact upon the rehabilitation of neglect: understanding the interaction of galvanic vestibular stimulation with allocentric visuospatial judgments in healthy volunteers may lead to the more effective deployment of such techniques in neurological patients.
电刺激前庭期间视觉空间忽视的暂时改善（《斯堪的纳维亚康复医学杂志》31卷（1999年）第117页）可能是由于纠正了由相关损伤导致的空间参考框架扭曲。在对神经疾病患者中这种效应的神经基础进行研究之前，需要先探究正常人中此类操作背后的神经机制，以便深入了解其生理基础。尽管电刺激（以及其他）前庭操作与视觉空间处理的相互作用（实际上还有人类如何计算空间参考框架的神经基础）具有临床意义，但其神经机制仍有待阐明。因此，我们利用功能磁共振成像对正常志愿者进行研究，以探究电刺激引起的以自我为中心的空间参考框架干扰对基于空间关系的视觉空间（直线二等分）判断背后的神经过程的影响。仅在右侧顶叶后部和腹侧运动前皮层观察到电刺激前庭与基于空间关系的视觉空间判断背后的神经机制之间存在显著的特定相互作用。先前发现在视觉空间忽视中受损的这些区域的激活表明，这些效应反映了在基于空间关系的空间任务中保持准确表现的同时，为补偿扭曲的以自我为中心的空间参考框架而增加的处理需求。因此，这些结果表明右侧顶叶后部和右侧腹侧运动前皮层参与了空间参考框架的计算。此外，我们的数据暗示了右侧半球损伤患者在电刺激前庭期间视觉空间忽视暂时改善的特定生理基础，因此可能会影响忽视的康复：了解健康志愿者中电刺激前庭与基于空间关系的视觉空间判断之间的相互作用，可能会使此类技术在神经疾病患者中得到更有效的应用。
