Harrison Richard, Gandhi Wiebke, van Reekum Carien M, Salomons Tim V
University of Reading, School of Psychology and Clinical Language Sciences, Reading, United Kingdom.
Department of Psychology, Queen's University, Kingston, ON, Canada.
Pain Rep. 2022 May 7;7(3):e999. doi: 10.1097/PR9.0000000000000999. eCollection 2022 May-Jun.
Conditioned pain modulation (CPM) is a psychophysical assessment used to estimate the efficiency of an individual's endogenous modulatory mechanisms. Conditioned pain modulation has been used as a predictive assessment for the development of chronic pain and responses to pain interventions. Although much is known about the spinal cord mechanisms associated with descending pain modulation, less is known about the contribution of supraspinal and especially cortical regions.
We aimed to explore how whole-brain connectivity of a core modulatory region, the periaqueductal grey (PAG), is associated with conditioned pain modulation, and endogenous pain modulation more broadly.
We measured CPM and resting-state connectivity of 35 healthy volunteers, absent of chronic pain diagnoses. As a region of interest, we targeted the PAG, which is directly involved in endogenous modulation of input to the spinal cord and is a key node within the descending pain modulation network.
We found that CPM was associated with heightened connectivity between the PAG and key regions associated with pain processing and inhibition, such as the primary and secondary somatosensory cortices, as well as the motor, premotor, and dorsolateral prefrontal cortices. These findings are consistent with connectivity findings in other resting-state and event-related fMRI studies.
These findings indicate that individuals who are efficient modulators have greater functional connectivity between the PAG and regions involved in processing pain. The heightened connectivity of these regions may contribute to the beneficial outcomes in clinical pain management, as quantified by CPM. These results may function as brain-based biomarkers for vulnerability or resilience to pain.
条件性疼痛调制（CPM）是一种用于评估个体内源性调制机制效率的心理物理学方法。条件性疼痛调制已被用作慢性疼痛发展及疼痛干预反应的预测性评估。尽管人们对与下行性疼痛调制相关的脊髓机制了解很多，但对脊髓以上尤其是皮质区域的贡献了解较少。
我们旨在探究核心调制区域中脑导水管周围灰质（PAG）的全脑连接性如何与条件性疼痛调制以及更广泛的内源性疼痛调制相关。
我们测量了35名无慢性疼痛诊断的健康志愿者的CPM和静息态连接性。作为感兴趣的区域，我们将目标定为PAG，它直接参与脊髓输入的内源性调制，并且是下行性疼痛调制网络中的关键节点。
我们发现CPM与PAG和与疼痛处理及抑制相关的关键区域（如初级和次级体感皮层以及运动、运动前和背外侧前额叶皮层）之间增强的连接性相关。这些发现与其他静息态和事件相关功能磁共振成像研究中的连接性发现一致。
这些发现表明，高效的调制者在PAG和参与疼痛处理的区域之间具有更强的功能连接性。这些区域增强的连接性可能有助于临床疼痛管理中获得有益结果，如通过CPM量化的那样。这些结果可能作为基于大脑的疼痛易感性或恢复力的生物标志物。
