Wörsching Jana, Padberg Frank, Helbich Konstantin, Hasan Alkomiet, Koch Lena, Goerigk Stephan, Stoecklein Sophia, Ertl-Wagner Birgit, Keeser Daniel
Department of Psychiatry and Psychotherapy, Ludwig-Maximilians-University, Munich, Germany.
Department of Psychiatry and Psychotherapy, Ludwig-Maximilians-University, Munich, Germany.
Neuroimage. 2017 Jul 15;155:187-201. doi: 10.1016/j.neuroimage.2017.04.052. Epub 2017 Apr 24.
Transcranial Direct Current Stimulation (tDCS) of the prefrontal cortex (PFC) can be used for probing functional brain connectivity and meets general interest as novel therapeutic intervention in psychiatric and neurological disorders. Along with a more extensive use, it is important to understand the interplay between neural systems and stimulation protocols requiring basic methodological work. Here, we examined the test-retest (TRT) characteristics of tDCS-induced modulations in resting-state functional-connectivity MRI (RS fcMRI). Twenty healthy subjects received 20minutes of either active or sham tDCS of the dorsolateral PFC (2mA, anode over F3 and cathode over F4, international 10-20 system), preceded and ensued by a RS fcMRI (10minutes each). All subject underwent three tDCS sessions with one-week intervals in between. Effects of tDCS on RS fcMRI were determined at an individual as well as at a group level using both ROI-based and independent-component analyses (ICA). To evaluate the TRT reliability of individual active-tDCS and sham effects on RS fcMRI, voxel-wise intra-class correlation coefficients (ICC) of post-tDCS maps between testing sessions were calculated. For both approaches, results revealed low reliability of RS fcMRI after active tDCS (ICC = -0.09 - 0.16). Reliability of RS fcMRI (baselines only) was low to moderate for ROI-derived (ICC = 0.13 - 0.50) and low for ICA-derived connectivity (ICC = 0.19 - 0.34). Thus, for ROI-based analyses, the distribution of voxel-wise ICC was shifted to lower TRT reliability after active, but not after sham tDCS, for which the distribution was similar to baseline. The intra-individual variation observed here resembles variability of tDCS effects in motor regions and may be one reason why in this study robust tDCS effects at a group level were missing. The data can be used for appropriately designing large scale studies investigating methodological issues such as sources of variability and localisation of tDCS effects.
经颅直流电刺激（tDCS）前额叶皮质（PFC）可用于探究功能性脑连接，作为治疗精神疾病和神经疾病的新型干预手段受到广泛关注。随着其应用的日益广泛，了解神经系统与刺激方案之间的相互作用变得尤为重要，这需要开展基础方法学研究。在此，我们研究了tDCS诱导的静息态功能连接磁共振成像（RS fcMRI）调制的重测（TRT）特征。20名健康受试者接受20分钟的背外侧PFC的主动或伪tDCS（2mA，阳极置于F3，阴极置于F4，国际10 - 20系统），刺激前后各进行一次RS fcMRI（每次10分钟）。所有受试者进行三次tDCS疗程，每次间隔一周。使用基于感兴趣区（ROI）和独立成分分析（ICA）在个体和群体水平上确定tDCS对RS fcMRI的影响。为评估个体主动tDCS和伪刺激对RS fcMRI影响的TRT可靠性，计算测试疗程之间tDCS后图谱的体素内类相关系数（ICC）。对于两种方法，结果均显示主动tDCS后RS fcMRI的可靠性较低（ICC = -0.09 - 0.16）。基于ROI的RS fcMRI（仅基线）可靠性为低到中度（ICC = 0.13 - 0.50），基于ICA的连接性可靠性较低（ICC = 0.19 - 0.34）。因此，对于基于ROI的分析，主动tDCS后体素水平ICC的分布向较低的TRT可靠性偏移，但伪tDCS后并非如此，其分布与基线相似。此处观察到的个体内变异类似于运动区域中tDCS效应的变异性，这可能是本研究中未观察到群体水平上显著tDCS效应的原因之一。这些数据可用于合理设计大规模研究，以探讨诸如变异性来源和tDCS效应定位等方法学问题。
