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首页> 外文期刊>The Journal of Neuroscience: The Official Journal of the Society for Neuroscience >Focal stimulation of the posterior parietal cortex increases the excitability of the ipsilateral motor cortex.
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Focal stimulation of the posterior parietal cortex increases the excitability of the ipsilateral motor cortex.

机译：顶叶后皮质的局部刺激增加了同侧运动皮层的兴奋性。

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摘要

Paired-pulse transcranial magnetic stimulation (TMS) has been applied as a probe to test functional connectivity within distinct cortical areas of the human motor system. Here, we tested the interaction between the posterior parietal cortex (PPC) and ipsilateral motor cortex (M1). A conditioning TMS pulse over the right PPC potentiates motor evoked-potentials evoked by a test TMS pulse over the ipsilateral motor cortex, with a time course characterized by two phases: an early peak at 4 ms interstimulus interval (ISI) and a late peak at 15 ms ISI. Activation of this facilitatory pathway depends on the intensity of stimulation, because the effects are induced with a conditioning stimulus of 90% resting motor threshold but not at lower or higher intensities. Similar results were obtained testing the ipsilateral interaction in the left hemisphere with a slightly different time course. In control experiments, we found that activation of this facilitatory pathway depends on the direction of induced current in the brain and is specific for stimulation of the caudal part of the inferior parietal sulcus (cIPS) site, because it is not observed for stimulation of adjacent scalp sites. Finally, we found that by using poststimulus time histogram analysis of single motor unit firing, the PPC conditioning increases the excitability of ipsilateral M1, enhancing the relative amount of late I wave input recruited by the test stimulus over M1, suggesting that such interaction is mediated by specific interneurons in the motor cortex. The described facilitatory connections between cIPS and M1 may be important in a variety of motor tasks and neuropsychiatric disorders.
机译：成对脉冲经颅磁刺激（TMS）已被用作探针来测试人体运动系统的不同皮质区域内的功能连通性。在这里，我们测试了后顶叶皮层（PPC）和同侧运动皮层（M1）之间的相互作用。右侧PPC上的调节TMS脉冲增强了同侧运动皮层上的测试TMS脉冲所诱发的运动诱发电位，其时程以两个阶段为特征：4 ms刺激间隔（ISI）的早期峰值和4ms的刺激峰值15毫秒ISI。该促进途径的激活取决于刺激的强度，因为这种影响是由90％静息运动阈值的条件刺激诱导的，而不是在较低或较高的强度下刺激的。测试左半球同侧相互作用的时间过程略有不同，获得了相似的结果。在对照实验中，我们发现该促进途径的激活取决于脑中感应电流的方向，并且对于刺激下顶沟（cIPS）的尾部是特异性的，因为未观察到对邻近顶沟的尾部的刺激头皮部位。最后，我们发现通过使用单个运动单位点火的刺激后时间直方图分析，PPC调节可增加同侧M1的兴奋性，从而增强测试刺激招募的相对于M1的晚期I波输入的相对量，表明这种相互作用是介导的通过运动皮层中特定的中间神经元。在各种运动任务和神经精神疾病中，cIPS与M1之间的便利连接可能很重要。

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