Lee Dongha, Guiomar Raquel, Gonçalves Óscar F, Almeida Jorge, Ganho-Ávila Ana
Cognitive Science Research Group, Korea Brain Research Institute, 61 Cheomdan-ro, Dong-gu, Daegu, Republic of Korea.
Center for Research in Neuropsychology and Cognitive Behavioral Intervention, Faculty of Psychology and Educational Sciences, University of Coimbra, Rua do Colégio Novo 3000-115, Coimbra, Portugal.
Int J Clin Health Psychol. 2023 Jan-Apr;23(1):100342. doi: 10.1016/j.ijchp.2022.100342. Epub 2022 Oct 15.
BACKGROUND/OBJECTIVE: Anxiety disorders are highly prevalent and negatively impact daily functioning and quality of life. Transcranial direct current stimulation (tDCS) targeting the dorsolateral prefrontal cortex (dlPFC), especially in the right hemisphere impacts extinction learning; however, the underlying neural mechanisms are elusive. Therefore, we aimed to investigate the effects of cathodal tDCS stimulation to the right dlPFC on neural activity and connectivity patterns during delayed fear extinction in healthy participants.
We conducted a two-day fear conditioning and extinction procedure. On the first day, we collected fear-related self-reports, clinical questionnaires, and skin conductance responses during fear acquisition. On the second day, participants in the tDCS group ( = 16) received 20-min offline tDCS before fMRI and then completed the fear extinction session during fMRI. Participants in the control group ( = 18) skipped tDCS and directly underwent fMRI to complete the fear extinction procedure. Whole-brain searchlight classification and resting-state functional connectivity analyses were performed.
Whole-brain searchlight classification during fear extinction showed higher classification accuracy of threat and safe cues in the left anterior dorsal and ventral insulae and hippocampus in the tDCS group than in the control group. Functional connectivity derived from the insula with the dlPFC, ventromedial prefrontal cortex, and inferior parietal lobule was increased after tDCS.
tDCS over the right dlPFC may function as a primer for information exchange among distally connected areas, thereby increasing stimulus discrimination. The current study did not include a sham group, and one participant of the control group was not randomized. Therefore, to address potential allocation bias, findings should be confirmed in the future with a fully randomized and sham controlled study.
背景/目的：焦虑症非常普遍，会对日常功能和生活质量产生负面影响。经颅直流电刺激（tDCS）靶向背外侧前额叶皮层（dlPFC），尤其是在右半球时会影响消退学习；然而，其潜在的神经机制尚不清楚。因此，我们旨在研究对健康参与者右侧dlPFC进行阴极tDCS刺激在延迟恐惧消退过程中对神经活动和连接模式的影响。
我们进行了为期两天的恐惧条件化和消退程序。第一天，我们在恐惧习得过程中收集了与恐惧相关的自我报告、临床问卷和皮肤电反应。第二天，tDCS组（n = 16）的参与者在功能磁共振成像（fMRI）之前接受20分钟的离线tDCS，然后在fMRI期间完成恐惧消退环节。对照组（n = 18）的参与者跳过tDCS，直接接受fMRI以完成恐惧消退程序。进行了全脑搜索light分类和静息态功能连接分析。
恐惧消退期间的全脑搜索light分类显示，tDCS组左侧前背侧和腹侧岛叶以及海马体中威胁和安全线索的分类准确率高于对照组。tDCS后，岛叶与dlPFC、腹内侧前额叶皮层和下顶叶小叶之间的功能连接增加。
右侧dlPFC上的tDCS可能作为远端连接区域之间信息交换的启动因素，从而提高刺激辨别能力。本研究未包括假刺激组，且对照组有一名参与者未随机分组。因此，为了解决潜在的分配偏倚问题，未来应通过完全随机和假刺激对照研究来证实研究结果。
