Unit of Neurology and Neurophysiology, Department of Medicine, Surgery and Neuroscience, University of Siena , Siena , Italy ; Brain Investigation and Neuromodulation Lab, University of Siena , Siena , Italy.
Brain Investigation and Neuromodulation Lab, University of Siena , Siena , Italy.
Front Psychiatry. 2014 Jul 21;5:86. doi: 10.3389/fpsyt.2014.00086. eCollection 2014.
While polarity-specific after-effects of monopolar transcranial direct current stimulation (tDCS) on corticospinal excitability are well-documented, modulation of vital parameters due to current spread through the brainstem is still a matter of debate, raising potential concerns about its use through the general public, as well as for neurorehabilitation purposes. We monitored online and after-effects of monopolar tDCS (primary motor cortex) in 10 healthy subjects by adopting a neuronavigated transcranial magnetic stimulation (TMS)/tDCS combined protocol. Motor evoked potentials (MEPs) together with vital parameters [e.g., blood pressure, heart-rate variability (HRV), and sympathovagal balance] were recorded and monitored before, during, and after anodal, cathodal, or sham tDCS. Ten MEPs, every 2.5-min time windows, were recorded from the right first dorsal interosseous (FDI), while 5-min epochs were used to record vital parameters. The protocol included 15 min of pre-tDCS and of online tDCS (anodal, cathodal, or sham). After-effects were recorded for 30 min. We showed a polarity-independent stabilization of cortical excitability level, a polarity-specific after-effect for cathodal and anodal stimulation, and an absence of persistent excitability changes during online stimulation. No significant effects on vital parameters emerged both during and after tDCS, while a linear increase in systolic/diastolic blood pressure and HRV was observed during each tDCS condition, as a possible unspecific response to experimental demands. Taken together, current findings provide new insights on the safety of monopolar tDCS, promoting its application both in research and clinical settings.
虽然单极经颅直流电刺激（tDCS）对皮质脊髓兴奋性的极性特异性后效已得到充分证实，但由于电流通过脑干扩散而对重要参数的调制仍存在争议，这引发了人们对其在普通公众中使用的潜在担忧，以及对神经康复的潜在担忧。我们通过采用神经导航经颅磁刺激（TMS）/tDCS 联合方案，在 10 名健康受试者中监测单极 tDCS（初级运动皮层）的在线和后效。在阳极、阴极或假刺激 tDCS 之前、期间和之后，我们记录并监测运动诱发电位（MEPs）以及重要参数[例如，血压、心率变异性（HRV）和交感神经-迷走神经平衡]。从右侧第一背侧骨间肌（FDI）记录 10 个 MEP，每 2.5 分钟记录一次窗口，同时使用 5 分钟的时间窗口记录重要参数。该方案包括 15 分钟的预 tDCS 和在线 tDCS（阳极、阴极或假刺激）。后效记录持续 30 分钟。我们显示了皮质兴奋性水平的非极性依赖性稳定，阴极和阳极刺激的极性特异性后效，以及在线刺激期间不存在持续兴奋性变化。tDCS 期间和之后都没有对重要参数产生显著影响，而在每个 tDCS 条件下都观察到收缩压/舒张压和 HRV 的线性增加，这可能是对实验要求的一种非特异性反应。综上所述，目前的研究结果为单极 tDCS 的安全性提供了新的见解，促进了其在研究和临床环境中的应用。
