Horvath Jared C, Carter Olivia, Forte Jason D
Psychological Sciences, University of Melbourne Melbourne, VIC, Australia.
Front Syst Neurosci. 2014 Jan 24;8:2. doi: 10.3389/fnsys.2014.00002. eCollection 2014.
Transcranial Direct Current Stimulation (tDCS) is a neuromodulatory device often publicized for its ability to enhance cognitive and behavioral performance. These enhancement claims, however, are predicated upon electrophysiological evidence and descriptions which are far from conclusive. In fact, a review of the literature reveals a number of important experimental and technical issues inherent with this device that are simply not being discussed in any meaningful manner. In this paper, we will consider five of these topics. The first, inter-subject variability, explores the extensive between- and within-group differences found within the tDCS literature and highlights the need to properly examine stimulatory response at the individual level. The second, intra-subject reliability, reviews the lack of data concerning tDCS response reliability over time and emphasizes the importance of this knowledge for appropriate stimulatory application. The third, sham stimulation and blinding, draws attention to the importance (yet relative lack) of proper control and blinding practices in the tDCS literature. The fourth, motor and cognitive interference, highlights the often overlooked body of research that suggests typical behaviors and cognitions undertaken during or following tDCS can impair or abolish the effects of stimulation. Finally, the fifth, electric current influences, underscores several largely ignored variables (such as hair thickness and electrode attachments methods) influential to tDCS electric current density and flow. Through this paper, we hope to increase awareness and start an ongoing dialog of these important issues which speak to the efficacy, reliability, and mechanistic foundations of tDCS.
经颅直流电刺激（tDCS）是一种神经调节设备，常因其增强认知和行为表现的能力而受到宣传。然而，这些增强效果的说法是基于远非确凿的电生理证据和描述。事实上，对文献的回顾揭示了该设备存在的一些重要实验和技术问题，而这些问题根本没有得到任何有意义的讨论。在本文中，我们将探讨其中五个主题。第一个主题是个体间变异性，探讨了tDCS文献中发现的组间和组内的广泛差异，并强调了在个体层面正确检查刺激反应的必要性。第二个主题是个体内可靠性，回顾了关于tDCS反应随时间的可靠性的数据缺失情况，并强调了这一知识对于适当刺激应用的重要性。第三个主题是假刺激和盲法，提请注意tDCS文献中适当对照和盲法实践的重要性（但相对缺乏）。第四个主题是运动和认知干扰，强调了经常被忽视的研究领域，该领域表明在tDCS期间或之后进行的典型行为和认知可能会削弱或消除刺激效果。最后，第五个主题是电流影响，强调了几个在很大程度上被忽视的变量（如头发厚度和电极附着方法）对tDCS电流密度和流动的影响。通过本文，我们希望提高对这些重要问题的认识，并开启关于这些问题的持续对话，这些问题涉及tDCS的疗效、可靠性和机制基础。
