Greeley Brian, Barnhoorn Jonathan S, Verwey Willem B, Seidler Rachael D
Department of Physical Therapy, University of British Columbia, Vancouver, BC, Canada.
Department of Learning, Data-Analytics and Technology, University of Twente, Enschede, Netherlands.
Front Hum Neurosci. 2022 Feb 24;16:814204. doi: 10.3389/fnhum.2022.814204. eCollection 2022.
Aging is associated with declines in sensorimotor function. Several studies have demonstrated that transcranial direct current stimulation (tDCS), a form of non-invasive brain stimulation, can be combined with training to mitigate age-related cognitive and motor declines. However, in some cases, the application of tDCS disrupts performance and learning. Here, we applied anodal tDCS either over the left prefrontal cortex (PFC), right PFC, supplementary motor complex (SMC), the left M1, or in a sham condition while older adults ( = 63) practiced a Discrete Sequence Production (DSP), an explicit motor sequence, task across 3 days. We hypothesized that stimulation to either the right or left PFC would enhance motor learning for older adults, based on the extensive literature showing increased prefrontal cortical activity during motor task performance in older adults. Contrary to our predictions, stimulation to the right and left PFC resulted in slowed motor learning, as evidenced by a slower reduction rate of reduction of reaction time and the number of sequence chunks across trials relative to sham in session one and session two, respectively. These findings suggest an integral role of the right PFC early in sequence learning and a role of the left PFC in chunking in older adults, and contribute to mounting evidence of the difficultly of using tDCS in an aging population.
衰老与感觉运动功能下降有关。多项研究表明，经颅直流电刺激（tDCS）作为一种非侵入性脑刺激形式，可与训练相结合，以减轻与年龄相关的认知和运动能力下降。然而，在某些情况下，tDCS的应用会干扰表现和学习。在此，我们对63名老年人在进行连续3天的离散序列生成（DSP，一种明确的运动序列）任务时，分别在左侧前额叶皮层（PFC）、右侧PFC、辅助运动复合体（SMC）、左侧M1区域施加阳极tDCS，或设置假刺激条件。基于大量文献表明老年人在执行运动任务时前额叶皮层活动增加，我们假设对右侧或左侧PFC的刺激会增强老年人的运动学习。与我们的预测相反，对右侧和左侧PFC的刺激导致运动学习减慢，这分别在第一天和第二天的试验中表现为反应时间和序列组块数量相对于假刺激组的下降速率更慢。这些发现表明右侧PFC在序列学习早期起着不可或缺的作用，左侧PFC在老年人的组块形成中发挥作用，并且进一步证明了在老年人群中使用tDCS存在困难。
