Abstract：
Prolonged experimental pain models can help assess cortical mechanisms underlying the transition from acute to chronic pain such as resting-state functional connectivity (rsFC), especially in early stages. This crossover study determined the effects of 24-hour-capsaicin-induced pain on the default mode network rsFC, a major network in the dynamic pain connectome. Electroencephalographic rsFC measured by Granger causality was acquired from 24 healthy volunteers (12 women) at baseline, 1hour, and 24hours following the application of a control or capsaicin patch on the right forearm. The control patch was received maximum 1 week before the capsaicin patch. Following 24hours, the patch was cooled and later heated to assess rsFC changes in response to pain relief and facilitation, respectively. Compared to baseline, decreased rsFC at alpha oscillations (8-10Hz) was found following 1hour and 24hours of capsaicin application for connections projecting from medial prefrontal cortex (mPFC) and right angular gyrus (rAG) but not left angular gyrus (lAG) or posterior cingulate cortex (PCC): mPFC-PCC (1hour:P < .001, 24hours:P = .002), mPFC-rAG (1hour:P < .001, 24hours:P = .001), rAG-mPFC (1hour:P < .001, 24hours:P = .001), rAG-PCC (1hour:P < .001, 24hours:P = .004). Comparable decreased rsFC following 1hour and 24hours (P≤0.008) was found at beta oscillations, however, decreased projections from PCC were also found: PCC-rAG (P≤0.005) and PCC-lAG (P≤0.006). Pain NRS scores following 24hours (3.7±0.4) was reduced by cooling (0.3±0.1, P = .004) and increased by heating (4.8±0.6, P = .016). However, neither cooling nor heating altered rsFC. This study shows that 24hours of experimental pain induces a robust decrease in DMN connectivity that persists during pain relief or facilitation suggesting a possible shift to attentional and emotional processing in persistent pain. PERSPECTIVE: This article shows decreased DMN connectivity that might reflect possible attentional and emotional changes during acute and prolonged pain. Understanding these changes could potentially help clinicians in developing therapeutic methods that can better target these attentional and emotional processes before developing into more persistent states.
摘要：
长时间的实验性疼痛可以帮助评估从急性到慢性疼痛过渡的皮质机制，例如静息状态功能连接（rsFC）。尤其是在早期阶段。这项交叉研究确定了辣椒素引起的24小时疼痛对默认模式网络rsFC的影响，动态疼痛连接体中的一个主要网络。通过Granger因果关系测量的脑电图rsFC在基线时从24名健康志愿者（12名女性）获得，1小时,在右前臂的对照或辣椒素贴片后24小时。对照贴剂在辣椒素贴剂之前最多接受一周。24小时后,将贴片冷却，然后加热以评估rsFC对疼痛缓解和促进反应的变化，分别。与基线相比，辣椒素应用1小时和24小时后，发现α振荡（8-10Hz）的rsFC降低，用于连接内侧前额叶皮层（mPFC）和右角回（rAG），但不包括左角回（lAG）或后扣带皮层（PCC）：mPFC-PCC（1小时：P<0.001，24小时：P=0.002），mPFC-rAG（1小时：P<0.001，24小时：P=0.001），rAG-mPFC（1小时：P<0.001，24小时：P=0.001），rAG-PCC(1小时:P<0.001,24小时:P=0.004)。在β振荡下发现1小时和24小时后rsFC的相当下降(P≤0.008)，然而,还发现PCC的预测减少：PCC-rAG（P≤0.005）和PCC-lAG（P≤0.006）。24小时后疼痛NRS评分（3.7±0.4）因冷却而降低（0.3±0.1，P=0.004），因加热而升高（4.8±0.6，P=0.016）。然而,冷却和加热都不会改变rsFC。这项研究表明，24小时的实验性疼痛会导致DMN连接的急剧下降，这种连接在疼痛缓解或促进过程中持续存在，这表明在持续性疼痛中可能转移到注意力和情绪处理。观点：本文显示了DMN连接的减少，这可能反映了急性和长期疼痛期间可能的注意力和情绪变化。了解这些变化可能有助于临床医生开发治疗方法，在发展成更持久的状态之前，更好地针对这些注意力和情绪过程。
