Moreno Marina L, Vanderhasselt Marie-Anne, Carvalho Andre F, Moffa Adriano H, Lotufo Paulo A, Benseñor Isabela M, Brunoni Andre R
Interdisciplinary Center for Applied Neuromodulation (CINA), University Hospital, University of São Paulo, São Paulo, Brazil.
Department of Experimental Clinical and Health Psychology, Ghent University, Ghent, Belgium.
Neurosci Lett. 2015 Mar 30;591:126-131. doi: 10.1016/j.neulet.2015.02.036. Epub 2015 Feb 20.
Dorsolateral prefrontal cortex (DLPFC) hypoactivity and subcortical hyperactivity have been associated to cognitive impairment for non-emotional ("cold") and emotional ("hot") working memory tasks in major depressive disorder (MDD). We investigated whether an increase of DLPFC activity using transcranial direct current stimulation (tDCS) would differently influence the performance in working memory tasks in depressed and healthy subjects. Forty young adult participants (20 with MDD and 20 healthy controls) were randomized to a single, sham-controlled, bifrontal (left anodal/right cathodal), 2mA, 30min tDCS session in a parallel design. The n-back and the internal shift task (IST) were used as proxies of cold and hot working memory performance, respectively. Active tDCS compared to sham promoted more accurate and faster responses to the n-back task for both patients and controls. Conversely, only patients presented an improvement in response times for the IST task. Our findings suggest that the mechanisms of tDCS in MDD involve modulation of both cold and hot working memory. We discuss these findings considering the modulatory top-down effects of tDCS on subcortical structures via prefrontal activation, and how spreading of activation might be different for healthy volunteers versus depressed patients. We also discuss the role of tDCS in cognitive amelioration for depressed patients. Finally, the distinct effects of tDCS in the "hot" cognition task for healthy and depressed participants are indicative that tDCS outcomes are also regulated by differences in baseline activity of the stimulated network.
背外侧前额叶皮质（DLPFC）功能减退及皮质下功能亢进与重度抑郁症（MDD）患者在非情感性（“冷”）和情感性（“热”）工作记忆任务中的认知障碍有关。我们研究了使用经颅直流电刺激（tDCS）增加DLPFC活动是否会对抑郁症患者和健康受试者在工作记忆任务中的表现产生不同影响。40名年轻成年参与者（20名MDD患者和20名健康对照）被随机分配到一个单组、假刺激对照、双侧额叶（左侧阳极/右侧阴极）、2mA、30分钟的tDCS治疗组，采用平行设计。n-back任务和内部转换任务（IST）分别用作冷工作记忆和热工作记忆表现的指标。与假刺激相比，主动tDCS使患者和对照组在n-back任务中的反应更准确、更快。相反，只有患者在IST任务中的反应时间有所改善。我们的研究结果表明，tDCS在MDD中的作用机制涉及对冷工作记忆和热工作记忆的调节。我们结合tDCS通过前额叶激活对皮质下结构的自上而下调节作用，以及健康志愿者与抑郁症患者激活扩散可能存在的差异来讨论这些发现。我们还讨论了tDCS在改善抑郁症患者认知方面的作用。最后，tDCS对健康参与者和抑郁症患者在“热”认知任务中的不同影响表明，tDCS的结果也受刺激网络基线活动差异的调节。
