Measuring Expectancy Effects of Transcranial Direct Current Stimulation on Motor Learning

项目总结/摘要 经颅直流电刺激（tDCS）是一种非侵入性脑刺激，它向头皮施加恒定的低水平直流电流以调节大脑兴奋性。虽然tDCS用于神经康复以增强运动学习，但支持这种用途的证据有些不确定，许多报告都没有发现。目前的研究设计没有充分控制参与者对tDCS的期望，这可能会对运动学习（以及认知，疼痛或焦虑）产生强大的安慰剂效应。长期目标是通过考虑以人为中心的脑刺激感知以及电刺激本身的影响来最大限度地提高运动学习。该R21应用的总体目标是证明关于tDCS（i）的期望在增强运动学习中发挥重要作用，独立于任何真实的刺激（即，tDCS的预期效果与治疗效果）和（ii）可以被利用以最大化tDCS在增强运动学习中的益处。中心假设是，对tDCS疗效的更高期望与运动练习后更多的技能改善相关，即使在安慰剂条件下（假tDCS）。该项目的基本原理是，考虑到人们对tDCS的期望，不仅可以提高未来tDCS研究的可重复性和严谨性，还可以最大限度地提高tDCS改善和恢复健康的整体效益。将通过追求两个特定目标来检验中心假设：1）确定tDCS的启动期望将调节运动技能学习的程度和2）确定假tDCS改善运动技能学习的程度。对于主要目的，在假刺激运动训练之前，将使用提示性信息来引导参与者的期望更积极或更消极。对于次要目的，将运动训练期间未预充tDCS的效果与完全未暴露于tDCS器械的对照组（仅运动训练）进行比较。在申请人看来，本申请中提出的研究是创新的，因为它通过考虑和测量参与者对tDCS的期望如何影响运动学习和康复，独立于刺激本身的任何效果，而与tDCS研究的现状有重大的不同。这项研究意义重大，因为它有望改变目前使用tDCS进行治疗的研究和临床实践范式。最终，采用综合健康方法，考虑人们对tDCS（和其他非侵入性脑刺激技术）的看法和期望，将对健康和医疗保健产生更大的影响，而不仅仅是关注电刺激本身的参数。

PROJECT SUMMARY/ABSTRACT Transcranial direct current stimulation (tDCS) is a type of non-invasive brain stimulation that applies constant, low levels of direct electrical current to the scalp to modulate brain excitability. While tDCS is used in neurorehabilitation to augment motor learning, the evidence supporting this use is somewhat inconclusive, with many reports of null findings. Current study designs do not adequately control for participants’ expectations about tDCS, which may exert a powerful placebo effect on motor learning (as well as cognition, pain, or anxiety). The long-term goal is to maximize motor learning by considering person-centered perceptions of brain stimulation in addition to the effects of electrical stimulation itself. The overall objectives in this R21 application are to demonstrate that expectations about tDCS (i) play a significant role in enhancing motor learning, independent of any real stimulation (i.e., an expectancy effect vs. a treatment effect of tDCS) and (ii) can be leveraged to maximize the benefits of tDCS in enhancing motor learning. The central hypothesis is that higher expectations about the efficacy of tDCS are associated with more skill improvement following motor practice, even in placebo conditions (sham tDCS). The rationale for this project is that considering people’s expectations about tDCS will not only improve the reproducibility and rigor of future tDCS research, but will also maximize the overall benefit of tDCS for improving and restoring health. The central hypothesis will be tested by pursuing two specific aims: 1) Determine the extent to which priming expectations of tDCS will modulate motor skill learning and 2) Determine the extent to which sham tDCS improves motor skill learning. For the primary aim, suggestive information will be used to prime participants’ expectations to be more positive or more negative prior to motor training with sham stimulation. For the secondary aim, the effects of unprimed tDCS during motor training will be compared to a control group with no exposure to the tDCS device at all (motor training only). The research proposed in this application in innovative, in the applicant’s opinion, because it is a major departure from the status quo of tDCS research by considering and measuring how participants’ expectations of tDCS affect motor learning and rehabilitation, independent from any effect of the stimulation itself. The proposed research is significant because it is expected to shift current research and clinical practice paradigms that use tDCS for treatment. Ultimately, adopting an integrative health approach that considers how people’s perceptions and expectations of tDCS (and other non-invasive brain stimulation techniques) will have a greater impact on health and health care than simply focusing on parameters of the electrical stimulation itself.