Martin-Garcia Oscar, da Silva Pedro Henrique Rodrigues, De Smet Stefanie, De Witte Sara, Brunoni Andre R, Vanderhasselt Marie-Anne, Razza Lais B
Department of Personality, Evaluation and Clinical Psychology, Complutense University of Madrid, Madrid, Spain.
Departamento e Instituto de Psiquiatria, Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo, São Paulo, Brazil; Division of Neuropsychiatry and Neuromodulation, Massachusetts General Hospital, Harvard Medical School, Boston, USA.
Behav Brain Res. 2025 Mar 12;481:115416. doi: 10.1016/j.bbr.2025.115416. Epub 2025 Jan 4.
Working memory is crucial for daily life and is often impaired in neuropsychiatric conditions. Attempts to enhance it using transcranial direct current stimulation (tDCS) have shown mixed results, possibly due to large inter-individual variability. This study assessed whether baseline regional brain volume was associated with working memory performance following tDCS. Healthy participants were randomly assigned to three bilateral tDCS protocols (sham, 1.5 mA, and 3 mA) over the dorsolateral prefrontal cortex (dlPFC) (anode-left, cathode-right) for 20 minutes, in a within-subjects design with a 2-week interval, followed by emotional and non-emotional 3-back tasks. Baseline volumetric data were used to extract gray matter volumes of defined regions of interest; the dlPFC, the medial PFC (mPFC), and the posterior cingulate cortex (PCC) bilaterally. Data from thirty-nine participants (69.2 % female, mean age: 24.56 years) across 112 tDCS sessions were analyzed. Findings revealed no significant association between working memory performance post sham-tDCS and gray matter volume. However, larger baseline cortical volumes across all regions were associated with slower reaction times and lower accuracy for the non-emotional task at 1.5 mA, whereas non-significant results were observed at 3 mA. For the emotional task, only a significant association for reaction time after 3 mA and left dlPFC and right PCC were found. Findings highlight not only the association between individual baseline gray matter, but also the impact of methodological choices, such as current intensity and outcome, on the effect of tDCS. Future research should aim to further explore individual variability and methodological factors to deepen our understanding of the mechanisms underlying tDCS.
工作记忆对日常生活至关重要，并且在神经精神疾病中常常受损。尝试使用经颅直流电刺激（tDCS）来增强工作记忆的研究结果不一，这可能是由于个体间存在较大差异。本研究评估了基线区域脑容量是否与tDCS后的工作记忆表现相关。健康参与者被随机分配到三种双侧tDCS方案（假刺激、1.5毫安和3毫安），刺激背外侧前额叶皮层（dlPFC）（阳极在左，阴极在右），持续20分钟，采用受试者内设计，间隔2周，随后进行情绪和非情绪的3-back任务。基线体积数据用于提取双侧定义感兴趣区域的灰质体积；即dlPFC、内侧前额叶皮层（mPFC）和后扣带回皮层（PCC）。对来自39名参与者（69.2%为女性，平均年龄：24.56岁）的112次tDCS治疗的数据进行了分析。研究结果显示，假刺激tDCS后的工作记忆表现与灰质体积之间没有显著关联。然而，所有区域较大的基线皮质体积与1.5毫安时非情绪任务的反应时间较慢和准确性较低相关，而在3毫安时观察到无显著结果。对于情绪任务，仅发现3毫安后反应时间与左侧dlPFC和右侧PCC之间存在显著关联。研究结果不仅突出了个体基线灰质之间的关联，还强调了方法学选择（如电流强度和结果）对tDCS效果的影响。未来的研究应旨在进一步探索个体差异和方法学因素，以加深我们对tDCS潜在机制的理解。
