Nonnekes Jorik, Arrogi Anass, Munneke Moniek A M, van Asseldonk Edwin H F, Oude Nijhuis Lars B, Geurts Alexander C, Weerdesteyn Vivian
Radboud University Medical Centre, Donders Institute for Brain, Cognition and Behaviour, Department of Rehabilitation, Nijmegen, The Netherlands.
Radboud University Medical Centre, Donders Institute for Brain, Cognition and Behaviour, Department of Neurology/Clinical Neurophysiology, Nijmegen, The Netherlands.
PLoS One. 2014 Sep 18;9(9):e107731. doi: 10.1371/journal.pone.0107731. eCollection 2014.
Transcranial direct current stimulation (tDCS) is a noninvasive brain stimulation technique that alters cortical excitability. Interestingly, in recent animal studies facilitatory effects of tDCS have also been observed on subcortical structures. Here, we sought to provide evidence for the potential of tDCS to facilitate subcortical structures in humans as well. Subjects received anodal-tDCS and sham-tDCS on two separate testing days in a counterbalanced order. After stimulation, we assessed the effect of tDCS on two responses that arise from subcortical structures; (1) wrist and ankle responses to an imperative stimulus combined with a startling acoustic stimulus (SAS), and (2) automatic postural responses to external balance perturbations with and without a concurrent SAS. During all tasks, response onsets were significantly faster following anodal-tDCS compared to sham-tDCS, both in trials with and without a SAS. The effect of tDCS was similar for the dominant and non-dominant leg. The SAS accelerated the onsets of ankle and wrist movements and the responses to backward, but not forward perturbations. The faster onsets of SAS-induced wrist and ankle movements and automatic postural responses following stimulation provide strong evidence that, in humans, subcortical structures--in particular the reticular formation--can be facilitated by tDCS. This effect may be explained by two mechanisms that are not mutually exclusive. First, subcortical facilitation may have resulted from enhanced cortico-reticular drive. Second, the applied current may have directly stimulated the reticular formation. Strengthening reticulospinal output by tDCS may be of interest to neurorehabilitation, as there is evidence for reticulospinal compensation after corticospinal lesions.
经颅直流电刺激（tDCS）是一种改变皮层兴奋性的非侵入性脑刺激技术。有趣的是，在最近的动物研究中，也观察到tDCS对皮层下结构有促进作用。在此，我们试图为tDCS在人类中促进皮层下结构的潜力提供证据。受试者在两个不同的测试日以平衡的顺序接受阳极tDCS和假tDCS。刺激后，我们评估了tDCS对两种源自皮层下结构的反应的影响；（1）手腕和脚踝对命令性刺激与惊声刺激（SAS）组合的反应，以及（2）对有和没有同时进行的SAS的外部平衡扰动的自动姿势反应。在所有任务中，与假tDCS相比，阳极tDCS后的反应起始明显更快，无论有无SAS的试验都是如此。tDCS对优势腿和非优势腿的影响相似。SAS加速了脚踝和手腕运动的起始以及对向后而非向前扰动的反应。刺激后SAS诱发的手腕和脚踝运动以及自动姿势反应的更快起始提供了有力证据，表明在人类中，皮层下结构——特别是网状结构——可以被tDCS促进。这种效应可能由两种并非相互排斥的机制来解释。首先，皮层下促进可能是由于增强的皮质-网状驱动。其次，施加的电流可能直接刺激了网状结构。通过tDCS增强网状脊髓输出可能对神经康复有益，因为有证据表明在皮质脊髓损伤后存在网状脊髓代偿。
