Department of Anatomy, Université du Québec à Trois-Rivières, Trois-Rivières, QC, Canada; CogNAC Research Group, Université du Québec à Trois-Rivières, Trois-Rivières, QC, Canada.
Department of Psychology, Université Laval, Québec, QC, Canada.
J Pain. 2021 Jul;22(7):797-805. doi: 10.1016/j.jpain.2021.02.001. Epub 2021 Feb 10.
Working memory (WM) engagement produces pain inhibition. However, it remains unclear whether higher WM load increases this effect. The aim of this study was to investigate the interaction between WM load and pain inhibition by WM and examine the contribution of cerebrospinal mechanism. Thirty-eight healthy volunteers were assigned to one of 2 n-back groups for which WM load was different (2-back or 3-back). The experimental protocol comprised 5 counterbalanced conditions (0-back, n-back, pain, 0-back with pain, and n-back with pain). Pain and the nociceptive flexion reflex (NFR) were evoked by transcutaneous electrical stimulation of the sural nerve. Pain was significantly different between conditions, but not between n-back groups. Both the 0-back and n-back tasks reduced pain compared with pain alone, but the n-back task produced stronger pain inhibition compared with the 0-back task. NFR amplitude was significantly different between conditions but not between n-back groups. NFR was inhibited by the 0-back and n-back tasks, with no difference between the 2 tasks. These findings indicate that pain inhibition by WM is increased by WM load, but only to a certain point. NFR inhibition by WM suggests that inhibition of pain by WM depends, at least in part, on cerebrospinal mechanism. PERSPECTIVE: This behavioral and electrophysiological study shows that engaging in a cognitive task reduces pain by decreasing spinal nociceptive transmission, depending on task difficulty. These findings may yield better nonpharmacological pain therapies based on individual differences in working memory performance and capacity as well as several factors that regulate working memory.
工作记忆（WM）的参与会产生疼痛抑制。然而，目前尚不清楚较高的 WM 负荷是否会增加这种效果。本研究旨在通过 WM 考察 WM 负荷与疼痛抑制之间的相互作用，并探讨中枢机制的贡献。38 名健康志愿者被分配到 2 个 n-back 组中的 1 个，这 2 个 n-back 组的 WM 负荷不同（2-back 或 3-back）。实验方案包括 5 个平衡条件（0-back、n-back、疼痛、0-back 伴有疼痛和 n-back 伴有疼痛）。通过刺激腓肠神经的经皮电刺激来诱发疼痛和伤害性屈反射（NFR）。疼痛在条件之间存在显著差异，但在 n-back 组之间没有差异。0-back 和 n-back 任务都能减轻疼痛，但 n-back 任务比 0-back 任务产生更强的疼痛抑制作用。NFR 幅度在条件之间存在显著差异，但在 n-back 组之间没有差异。0-back 和 n-back 任务都抑制了 NFR，这两种任务之间没有差异。这些发现表明，WM 对疼痛的抑制作用随着 WM 负荷的增加而增加，但仅在一定程度上增加。WM 对 NFR 的抑制表明，WM 对疼痛的抑制至少部分取决于中枢机制。观点：这项行为和电生理研究表明，通过降低脊髓伤害性传入传递，认知任务参与会减轻疼痛，这取决于任务难度。这些发现可能会产生更好的非药物性疼痛治疗方法，这些方法基于工作记忆表现和能力的个体差异以及调节工作记忆的几个因素。
