BACKGROUND Transcranial direct current stimulation (tDCS) has been shown to improve working memory (WM) performance in healthy individuals, however effects tend to be modest and variable. Transcranial random noise stimulation (tRNS) can be delivered with a direct-current offset (DC-offset) to induce equal or even greater effects on cortical excitability than tDCS. To-date, no research has directly compared the effects of these techniques on WM performance or underlying neurophysiological activity. OBJECTIVE To compare the effects of anodal tDCS, tRNS + DC-offset, or sham stimulation over the left dorsolateral prefrontal cortex (DLPFC) on WM performance and task-related EEG oscillatory activity in healthy adults. METHODS Using a between-subjects design, 49 participants were allocated to receive either anodal tDCS (N = 16), high-frequency tRNS + DC-offset (N = 16), or sham stimulation (N = 17) to the left DLPFC. Changes in WM performance were assessed using the Sternberg WM task completed before and 5- and 25-minutes post-stimulation. Event-related synchronisation/desynchronisation (ERS/ERD) of oscillatory activity was analysed from EEG recorded during WM encoding and maintenance. RESULTS tRNS induced more pronounced and consistent enhancements in WM accuracy when compared to both tDCS and sham stimulation. Improvements in WM performance following tRNS were accompanied by increased theta ERS and diminished gamma ERD during WM encoding, which were significantly greater than those observed following anodal tDCS or sham stimulation. CONCLUSIONS These findings demonstrate the potential of tRNS + DC-offset to modulate cognitive and electrophysiological measures of WM and raise the possibility that tRNS + DC-offset may be more effective and reliable than tDCS for enhancing WM performance in healthy individuals.

中文翻译：

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经颅随机噪声刺激比经颅直流电刺激更有效增强健康个体的工作记忆：行为和电生理证据

背景经颅直流电刺激(tDCS) 已被证明可以改善健康个体的工作记忆(WM) 表现，但是效果往往是适度和可变的。经颅随机噪声刺激 (tRNS) 可以通过直流偏移 (DC-offset) 进行传递，以对皮层兴奋性产生与 tDCS 相同甚至更大的影响。迄今为止，还没有研究直接比较这些技术对 WM 表现或潜在神经生理活动的影响。目的 比较阳极 tDCS、tRNS + DC 偏移或假刺激对左侧背外侧前额叶皮层 (DLPFC) 的影响对健康成人的 WM 表现和与任务相关的 EEG 振荡活动的影响。方法 使用受试者间设计，49 名参与者被分配接受阳极 tDCS（N = 16），高频 tRNS + DC 偏移（N = 16），或对左侧 DLPFC 的假刺激（N = 17）。使用在刺激前和刺激后 5 分钟和 25 分钟完成的 Sternberg WM 任务评估 WM 性能的变化。从 WM 编码和维护期间记录的 EEG 分析振荡活动的事件相关同步/去同步 (ERS/ERD)。结果 与 tDCS 和假刺激相比，tRNS 诱导 WM 准确性更显着和一致的增强。tRNS 后 WM 性能的改善伴随着 WM 编码期间 theta ERS ​​的增加和 gamma ERD 的减少，这明显大于阳极 tDCS 或假刺激后观察到的那些。