Center for Neuroplasticity and Pain (CNAP), Aalborg University, Aalborg, Denmark.
Pain. 2021 Jun 1;162(6):1659-1668. doi: 10.1097/j.pain.0000000000002187.
High-definition transcranial direct current stimulation (HD-tDCS) of brain areas related to pain processing may provide analgesic effects evident in the sensory detection and pain thresholds. The somatosensory sensitivity was assessed after HD-tDCS targeting the primary motor cortex (M1) and/or the dorsolateral prefrontal cortex (DLPFC). Eighty-one (40 females) subjects were randomly assigned to 1 of 4 anodal HD-tDCS protocols (20 minutes) applied on 3 consecutive days: Sham-tDCS, DLPFC-tDCS, M1-tDCS, and DLPFC&M1-tDCS (simultaneous transcranial direct current stimulation [tDCS] of DLPFC and M1). Subjects and experimenter were blinded to the tDCS protocols. The somatosensory sensitivity were assessed each day, before and after each tDCS by detection and pain thresholds to thermal and mechanical skin stimulation, vibration detection thresholds, and pressure pain thresholds. Subjects were effectively blinded to the protocol, with no significant difference in rates of whether they received real or placebo tDCS between the 4 groups. Compared with the Sham-tDCS, none of the active HD-tDCS protocols caused significant changes in detection or pain thresholds. Independent of tDCS protocols, pain and detection thresholds except vibration detection were increased immediately after the first tDCS protocol compared with baseline (P < 0.05). Overall, the active stimulation protocols were not able to induce significant modulation of the somatosensory thresholds in this healthy population compared with sham-tDCS. Unrelated to the HD-tDCS protocol, a decreased sensitivity was found after the first intervention, indicating a placebo effect or possible habituation to the quantitative sensory testing assessments. These findings add to the increasing literature of null findings in the modulatory effects of HD-tDCS on the healthy somatosensory system.
高清晰度经颅直流电刺激(HD-tDCS)对与疼痛处理相关的脑区可能提供明显的镇痛作用,表现在感觉检测和疼痛阈值上。在对初级运动皮层(M1)和/或背外侧前额叶皮层(DLPFC)进行 HD-tDCS 靶向治疗后,评估体感敏感性。81 名(40 名女性)受试者被随机分配到 1 种 4 种阳极 HD-tDCS 方案(20 分钟)中,连续 3 天应用:假刺激 tDCS、DLPFC-tDCS、M1-tDCS 和 DLPFC&M1-tDCS(DLPFC 和 M1 的同时经颅直流电刺激[tDCS])。受试者和实验者对 tDCS 方案均不知情。在每次 tDCS 之前和之后,通过热和机械皮肤刺激、振动检测阈值和压力疼痛阈值,每天评估体感敏感性。与假刺激 tDCS 相比,4 组之间接受真实或安慰剂 tDCS 的受试者比例没有显著差异,表明受试者有效地被蒙蔽。与假刺激 tDCS 相比,没有任何一种主动 HD-tDCS 方案引起检测或疼痛阈值的显著变化。与 tDCS 方案无关,与基线相比,第一次 tDCS 方案后除振动检测外,疼痛和检测阈值均立即增加(P<0.05)。总体而言,与假刺激 tDCS 相比,在健康人群中,主动刺激方案不能引起体感阈值的显著调节。与 HD-tDCS 方案无关,首次干预后发现敏感性降低,表明存在安慰剂效应或对定量感觉测试评估的可能习惯化。这些发现增加了关于 HD-tDCS 对健康体感系统的调节作用的越来越多的无发现文献。
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