中文摘要：

目的：探讨单侧后顶叶皮质的过度活动是否会造成对侧同源脑区的功能抑制并影响空间定向功能。方法：按照一定的人选标准选取健康受试者30人，采用兴奋性间歇性短阵快速脉冲刺激，随机对左／右侧后顶叶皮质进行真／假刺激，结合注意网络测试系统评定受试者视空间注意功能的变化。结果：间歇性短阵快速脉冲刺激右侧后顶叶皮质，可以提高警觉及定向功能（P＜0．05）；刺激左侧后顶叶皮质，定向功能受损（P＜0．05）。结论：右侧后顶叶是空间定向活动的关键脑区，左侧后顶叶过度活动可以导致右侧后顶叶功能抑制。建立双侧半球间新的竞争性平衡，对实现单侧后顶叶损害空间定向功能的康复具有重要意义。

英文摘要：

Objective： To seek more direct evidences whether the hyperactivity of unilateral posterior parietal cortex （PPC） could decrease the excitability of the contralateral homologous cortex in humans. Method： Sixty healthy subjects were selected for this study. All subjects received the intermittent theta burst stimulation （i-TBS） over the left or right PPC and then were tested for the attention network test （ANT）. The ANT provided measures for three different components of visual attention： alerting, orienting and executive control. Result： All subjects finished this task without significant side effects. During this task, there was no significant interaction in the mean response time（RT） among none-, center-, double- and spatial-cue conditions among the real or sham i-TBS to the left or right PPC conditions. The efficiencies of alerting and orienting improved after real right PPC i-TBS in participants. However, the real left-PPC i-TBS resulted in significant deficit in the efficiency of spatial orienting. Compared with the sham i-TBS, there was no significant difference in executive control index in the real i-TBS condition. Conclusion： These results suggest that the right PPC plays an important role in spatial orienting function. What is more, this present study demonstrates that hyperactivity of unilateral posterior parietal cortex decreases the excitability of contralateral homologous cortex through inter-hemispheric competition in the spatial orienting attention. Thus, the TBS maybe become an effective way to resolve some visuospatial neglect in patients withunilateral brain damage. Author＇s address Department of Rehabilitation Medicine, the First Affiliated Hospital of Sun Yat-Sen University, Guangzhou, 510080.