Pain is a subjective experience with significant individual differences. Laboratory studies investigating pain thresholds and experimental acute pain have identified structural and functional neural correlates. However, these types of pain stimuli have limited ecological validity to real-life pain experiences. Here, we use an orthodontic procedure-the insertion of an elastomeric separator between teeth-which typically induces mild to moderate pain that peaks within 2 days and lasts several days. We aimed to determine whether the baseline structure and resting-state functional connectivity of key regions along the trigeminal nociceptive and pain modulatory pathways correlate with subsequent peak pain ratings. Twenty-six healthy individuals underwent structural and resting-state functional MRI scanning before the placement of a separator between the first molar and second premolar, which was kept in place for 5 days. Participants recorded pain ratings 3 times daily on a 100-mm visual analogue scale. Peak pain was not significantly correlated with diffusion metrics of the trigeminal nerve or gray matter volume of any brain region. Peak pain did, however, positively correlate with baseline resting-state functional connectivity between the thalamus contralateral to the separator and bilateral insula, and negatively correlated with connectivity between the periaqueductal gray (PAG) and core nodes of the default mode network (medial prefrontal and posterior cingulate cortices). The ascending (thalamic) nociceptive and the descending (PAG) pain modulatory pathways at baseline each explained unique variation in peak pain intensity ratings. In sum, preinterventional functional neural architecture of both systems determined the individual pain experience to a subsequent ecologically valid pain stimulus.

中文翻译：

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基线静息状态功能连通性决定了随后的疼痛等级，以进行口腔面部疼痛的滋补生态有效实验模型。

疼痛是一种主观体验，具有显着的个体差异。调查疼痛阈值和实验性急性疼痛的实验室研究已经确定了结构和功能神经相关性。然而，这些类型的疼痛刺激对现实生活中的疼痛体验的生态有效性有限。在这里，我们使用正畸手术——在牙齿之间插入弹性分离器——通常会引起轻度至中度疼痛，在 2 天内达到峰值并持续数天。我们旨在确定沿三叉神经痛觉和疼痛调节通路的关键区域的基线结构和静息状态功能连接是否与随后的峰值疼痛等级相关。26 名健康人在第一磨牙和第二前磨牙之间放置分离器之前接受了结构和静息状态功能 MRI 扫描，分离器放置了 5 天。参与者每天在 100 毫米视觉模拟量表上记录疼痛等级 3 次。峰值疼痛与三叉神经的扩散指标或任何大脑区域的灰质体积没有显着相关性。然而，峰值疼痛确实与分离器对侧丘脑和双侧脑岛之间的基线静息状态功能连接呈正相关，与导水管周围灰质 (PAG) 和默认模式网络核心节点（内侧前额叶和后扣带皮层）。基线处的上行（丘脑）伤害性和下行 (PAG) 疼痛调节通路各自解释了峰值疼痛强度等级的独特变化。总之，两个系统的介入前功能神经结构决定了个体对随后的生态有效疼痛刺激的疼痛体验。