Dombrowe Isabel, Juravle Georgiana, Alavash Mohsen, Gießing Carsten, Hilgetag Claus C
Department of Experimental Psychology, Otto-von-Guericke-University Magdeburg, Magdeburg, Germany; Department of Computational Neuroscience, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
Department of Computational Neuroscience, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; Department of Systems Neuroscience, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
PLoS One. 2015 May 13;10(5):e0126802. doi: 10.1371/journal.pone.0126802. eCollection 2015.
Repetitive transcranial magnetic stimulation (rTMS) of the posterior parietal cortex (PPC) at frequencies lower than 5 Hz transiently inhibits the stimulated area. In healthy participants, such a protocol can induce a transient attentional bias to the visual hemifield ipsilateral to the stimulated hemisphere. This bias might be due to a relatively less active stimulated hemisphere and a relatively more active unstimulated hemisphere. In a previous study, Jin and Hilgetag (2008) tried to switch the attention bias from the hemifield ipsilateral to the hemifield contralateral to the stimulated hemisphere by applying high frequency rTMS. High frequency rTMS has been shown to excite, rather than inhibit, the stimulated brain area. However, the bias to the ipsilateral hemifield was still present. The participants' performance decreased when stimuli were presented in the hemifield contralateral to the stimulation site. In the present study we tested if this unexpected result was related to the fact that participants were passively resting during stimulation rather than performing a task. Using a fully crossed factorial design, we compared the effects of high frequency rTMS applied during a visual detection task and high frequency rTMS during passive rest on the subsequent offline performance in the same detection task. Our results were mixed. After sham stimulation, performance was better after rest than after task. After active 10 Hz rTMS, participants' performance was overall better after task than after rest. However, this effect did not reach statistical significance. The comparison of performance after rTMS with task and performance after sham stimulation with task showed that 10 Hz stimulation significantly improved performance in the whole visual field. Thus, although we found a trend to better performance after rTMS with task than after rTMS during rest, we could not reject the hypothesis that high frequency rTMS with task and high frequency rTMS during rest equally affect performance.
以低于5赫兹的频率对顶叶后部皮质（PPC）进行重复经颅磁刺激（rTMS）会短暂抑制受刺激区域。在健康参与者中，这样的方案会诱发对受刺激半球同侧视野的短暂注意力偏向。这种偏向可能是由于受刺激半球相对不活跃，而未受刺激半球相对更活跃。在之前的一项研究中，Jin和Hilgetag（2008年）试图通过应用高频rTMS将注意力偏向从受刺激半球的同侧视野切换到对侧视野。高频rTMS已被证明会兴奋而非抑制受刺激的脑区。然而，对同侧视野的偏向仍然存在。当刺激出现在与刺激部位对侧的视野中时，参与者的表现会下降。在本研究中，我们测试了这个意外结果是否与参与者在刺激期间被动休息而非执行任务这一事实有关。我们采用完全交叉析因设计，比较了在视觉检测任务期间应用高频rTMS和在被动休息期间应用高频rTMS对同一检测任务后续离线表现的影响。我们的结果喜忧参半。在伪刺激后，休息后的表现比任务后的表现更好。在进行10赫兹的有效rTMS后，参与者在任务后的整体表现比休息后更好。然而，这种效应未达到统计学显著性。rTMS任务后表现与伪刺激任务后表现的比较表明，10赫兹刺激显著提高了整个视野的表现。因此，尽管我们发现rTMS任务后比rTMS休息后表现有更好的趋势，但我们不能拒绝任务期间高频rTMS和休息期间高频rTMS对表现有同等影响的假设。
