Enhancement of pain inhibition by working memory with anodal transcranial direct current stimulation of the left dorsolateral prefrontal cortex
The aim of this study was to examine whether transcranial direct current stimulation (tDCS) of the dorsolateral prefrontal cortex (DLPFC) enhances pain inhibition by improving working memory (WM). Forty healthy volunteers participated in two tDCS sessions. Pain was evoked by electrical stimulation at the ankle. Participants performed an n-back task (0-back and 2-back). The experimental protocol comprised five counterbalanced conditions (0-back, 2-back, pain, 0-back with pain and 2-back with pain) that were performed twice (pre-tDCS baseline and during tDCS). Compared with the pre-tDCS baseline values, anodal tDCS decreased response times for the 2-back condition (p < 0.01) but not for the 0-back condition (p > 0.5). Anodal tDCS also decreased pain ratings marginally in the 2-back with pain condition, but not the 0-back with pain condition (p = 0.052 and p > 0.2, respectively). No effect was produced by sham tDCS for any condition (p > 0.2). These results indicate that tDCS of the left DLPFC may enhance pain inhibition by improving WM.
KeywordsNeuromodulation Nociceptive Cognition Descending modulation Anxiety
ZD contributed to all aspects of the research. SB contributed to data acquisition, analyses and interpretation. NR contributed to data acquisition and interpretation. IB contributed to experimental design, data interpretation and manuscript preparation. MP contributed to all aspects of the research and obtained funding for the study.
This study was supported by a grant from the Natural Sciences and Engineering Research Council of Canada to MP (402176). The contribution of MP was supported by the research Chair in Pain Neurophysiology from “Université du Québec à Trois-Rivières” (UQTR), the “Fonds de Recherche du Québec en Santé (FRQS) and the “Fondation de Recherche en Chiropratique du Québec. The contribution of Zoha Deldar was supported by the department of Anatomy at UQTR.
Compliance with ethical standards
All experimental procedures conformed to the standards set by the latest revision of the Declaration of Helsinki and were approved by the Research Ethics Board of Université du Québec à Trois-Rivières. All participants gave written informed consent, acknowledging their right to withdraw from the experiment without prejudice.
Conflict of interest
Zoha Deldar reports no financial or other relationship that may lead to any conflict of interest. Nabi Rustamov reports no financial or other relationship that may lead to any conflict of interest. Suzie Bois reports no financial or other relationship that may lead to any conflict of interest. Isabelle Blanchette reports no financial or other relationship that may lead to any conflict of interest. Mathieu Piché reports no financial or other relationship that may lead to any conflict of interest.
- 7.Torta DM, Legrain V, Mouraux A, Valentini E (2017) Attention to pain! A neurocognitive perspective on attentional modulation of pain in neuroimaging studies. CortexGoogle Scholar
- 41.Awh E, Jonides J (2001) Overlapping mechanisms of attention and spatial working memory. Elsevier, London, pp 119–126Google Scholar
- 66.Ladouceur A, Rustamov N, Dubois JD, Tessier J, Lehmann A, Descarreaux M, Rainville P, Piche M (2017) Inhibition of pain and pain-related brain activity by heterotopic noxious counter-stimulation and selective attention in chronic non-specific low back pain. Neuroscience. https://doi.org/10.1016/j.neuroscience.2017.09.054