Department of Rehabilitation Medicine, The Third Affiliated Hospital, Sun Yat-sen University, 600 Tianhe Road, Tianhe District, Guangzhou, Guangdong, China.
Department of Psychology, College of Arts and Sciences, New York University, New York, NY, 10003, USA.
J Neuroeng Rehabil. 2024 Nov 8;21(1):201. doi: 10.1186/s12984-024-01498-4.
Working memory is critical for individuals and has been found to be improved by electrical stimulation of the left dorsolateral prefrontal cortex (DLPFC). However, the effects of different types of transcranial electrical stimulation on working memory are controversial, and the underlying mechanism remains uncertain. In this study, high-definition transcranial direct current stimulation (HD-tDCS) and high-definition transcranial random noise stimulation (HD-tRNS) were applied to the DLPFC to observe the different effects on visual working memory (VWM). The aim was to explore the causal relationship between the electrical activity of the DLPFC and the posterior parietal cortex (PPC) electrical activity and the contralateral delayed activity (CDA).
Thirty-three healthy subjects received HD-tDCS, HD-tRNS and sham stimulation in a random order. Stimulation was applied to the left DLPFC for 20 min. The subjects underwent a color change-detection task as our VWM task and an auditory digit span test (DST) immediately after stimulation. Event-related potential (ERP) data were collected during the VWM task.
The results revealed significant differences between the different types of HD-tES. There was a remarkable increase in VWM capacity following HD-tDCS compared with both HD-tRNS (p = 0.038) and sham stimulation (p = 0.038). Additionally, the CDA from the PPC differed after stimulation of the DLPFC. Both HD-tDCS and HD-tRNS expanded the maximum CDA amplitude from set size of 4 to 6, whereas after sham stimulation, the maximum CDA was maintained at a set size of 4. Compared with the sham condition, only HD-tDCS induced a noteworthy increase in CDA amplitude (p = 0.012). Notably, a significant correlation emerged between the mean CDA amplitude and VWM capacity (p < 0.001, r = - 0.402).
These findings underscore the ability of HD-tDCS to target the DLPFC to augment working memory capacity while concurrently amplifying CDA amplitudes in the PPC through the frontoparietal network. Trial registration ChiCTR2300074898.
工作记忆对于个体至关重要，现已证实其可通过左背外侧前额叶皮层（DLPFC）的电刺激得到改善。然而，不同类型的经颅电刺激对工作记忆的影响存在争议，其潜在机制尚不清楚。在本研究中，我们应用高清晰度经颅直流电刺激（HD-tDCS）和高清晰度经颅随机噪声刺激（HD-tRNS）于 DLPFC，观察其对视觉工作记忆（VWM）的不同影响。旨在探讨 DLPFC 与对侧延迟活动（CDA）的电活动以及顶叶后皮质（PPC）电活动之间的因果关系。
33 名健康受试者以随机顺序接受 HD-tDCS、HD-tRNS 和假刺激。刺激持续 20 分钟，施加于左侧 DLPFC。刺激后，受试者立即进行颜色变化检测任务作为我们的 VWM 任务和听觉数字跨度测试（DST）。在 VWM 任务中采集事件相关电位（ERP）数据。
不同类型的 HD-tES 之间存在显著差异。与 HD-tRNS（p=0.038）和假刺激（p=0.038）相比，HD-tDCS 后 VWM 容量显著增加。此外，刺激 DLPFC 后，PPC 的 CDA 也发生了变化。HD-tDCS 和 HD-tRNS 均使从设定大小 4 到 6 的最大 CDA 幅度扩大，而在假刺激后，最大 CDA 保持在设定大小 4。与假刺激相比，只有 HD-tDCS 显著增加了 CDA 幅度（p=0.012）。值得注意的是，平均 CDA 幅度与 VWM 容量之间存在显著相关性（p<0.001，r=-0.402）。
这些发现强调了 HD-tDCS 通过前额顶叶网络靶向 DLPFC 以增强工作记忆容量，同时放大 PPC 中的 CDA 幅度的能力。试验注册 ChiCTR2300074898。
