Jor'dan Azizah J, Bernad-Elazari Hagar, Mirelman Anat, Gouskova Natalia A, Lo On-Yee, Hausdorff Jeffrey M, Manor Brad
Department of Exercise and Health Sciences, University of Massachusetts Boston, Boston, MA, United States.
Hinda and Arthur Marcus Institute for Aging Research, Hebrew SeniorLife, Boston, MA, United States.
Front Aging Neurosci. 2022 Mar 11;14:843122. doi: 10.3389/fnagi.2022.843122. eCollection 2022.
Transcranial direct current stimulation (tDCS) targeting the left dorsolateral prefrontal cortex (dlPFC) improves dual task walking in older adults, when tested just after stimulation. The acute effects of tDCS on the cortical physiology of walking, however, remains unknown.
In a previous study, older adults with slow gait and executive dysfunction completed a dual task walking assessment before and after 20 min of tDCS targeting the left dlPFC or sham stimulation. In a subset of seven participants per group, functional near-infrared spectroscopy (fNIRS) was used to quantify left and right prefrontal recruitment defined as the oxygenated hemoglobin response to usual and dual task walking (ΔHbO2), as well as the absolute change in this metric from usual to dual task conditions (i.e., ΔHbO2 ). Paired -tests examined pre- to post-stimulation differences in each fNIRS metric within each group.
The tDCS group exhibited pre- to post-stimulation reduction in left prefrontal ΔHbO2 ( = 0.03). This mitigation of dual task "cost" to prefrontal recruitment was induced primarily by a reduction in left prefrontal ΔHbO2 ( = 0.001), an effect that was observed in all seven participants within this group. Sham stimulation did not influence ΔHbO2 or ΔHbO2 in either walking condition ( > 0.35), and neither tDCS nor sham substantially influenced right prefrontal recruitment ( > 0.16).
This preliminary fNIRS data suggests that tDCS over the left dlPFC may modulate prefrontal recruitment, as reflected by a relative reduction in the oxygen consumption of this brain region in response to dual task walking.
经颅直流电刺激（tDCS）靶向左侧背外侧前额叶皮质（dlPFC）可改善老年人的双任务步行能力，这一效果在刺激后即刻测试时得到验证。然而，tDCS对步行时皮质生理学的急性影响仍不清楚。
在之前的一项研究中，步态缓慢且存在执行功能障碍的老年人在接受20分钟靶向左侧dlPFC的tDCS或假刺激前后，完成了双任务步行评估。在每组七名参与者的子集中，使用功能近红外光谱（fNIRS）来量化左右前额叶的激活情况，将其定义为对常规和双任务步行的氧合血红蛋白反应（ΔHbO2），以及该指标从常规任务到双任务条件下的绝对变化（即ΔHbO2 ）。配对t检验用于检查每组内每个fNIRS指标在刺激前后的差异。
tDCS组在刺激前后左侧前额叶ΔHbO2 有所降低（ = 0.03）。双任务对前额叶激活的“成本”降低主要是由左侧前额叶ΔHbO2 的减少引起的（ = 0.001），该组内所有七名参与者均观察到这一效应。假刺激在任何一种步行条件下均未影响ΔHbO2 或ΔHbO2 （ > 0.35），tDCS和假刺激对右侧前额叶激活均无显著影响（ > 0.16）。
这些初步的fNIRS数据表明，左侧dlPFC上的tDCS可能调节前额叶的激活，这表现为该脑区在双任务步行时的氧消耗相对减少。
