Department of Neuroimaging, King's College London, London, UK.
Wolfson Centre for Age Related Diseases, King's College London, London, UK.
Eur J Pain. 2020 Oct;24(9):1850-1861. doi: 10.1002/ejp.1633. Epub 2020 Jul 27.
Functional connectivity (FC) perturbations have been reported in multiple chronic pain phenotypes, but the nature of reported changes varies between cohorts and may relate to the consequences of living with chronic-pain related comorbidities, such as anxiety and depression. Healthy volunteer studies provide opportunities to study the effects of tonic noxious stimulation independently of these sequelae. Connectivity changes in task negative and positive networks, for example, the default mode and salience networks (DMN/SN), respectively, have been described, but how these and other connectivity networks, for example, those governing descending pain control are affected by the presence of tonic, noxious stimulation in healthy, pain-free individuals, remains unknown.
In 20 healthy volunteers, we assessed FC prior to, during, and following tonic cold painful stimulation in the ventromedial prefrontal cortex (vmPFC), rostral anterior insula (rAI), subgenual anterior cingulate cortex (ACC) and periaqueductal grey (PAG). We also recorded subjectively reported pain using a computerised visual analogue scale.
We saw DMN FC changes during painful stimulation and that inter-network connectivity between the rAI with the vmPFC increased during pain, whereas PAG-precuneus FC decreased. Pain-induced FC alterations persisted following noxious stimulation. FC changes related to the magnitude of individuals' subjectively reported pain.
We demonstrate FC changes during and following tonic cold-pain in healthy participants. Similarities between our findings and reports of patients with chronic pain suggest that some FC changes observed in these patients may relate to the presence of an ongoing afferent nociceptive drive.
How pain-related resting state networks are affected by tonic cold-pain remains unknown. We investigated functional connectivity alterations during and following tonic cold pain in healthy volunteers. Cold pain perturbed the functional connectivity of the ventro-medial prefrontal cortex, anterior insula, and the periacquaductal grey area. These connectivity changes were associated with the magnitude of individuals' reported pain. We suggest that some connectivity changes described in chronic pain patients may be due to an ongoing afferent peripheral drive.
功能连接（FC）的改变已经在多种慢性疼痛表型中被报道，但报道的变化性质在不同队列之间存在差异，可能与慢性疼痛相关合并症（如焦虑和抑郁）的后果有关。健康志愿者研究提供了独立于这些后遗症研究持续有害刺激的影响的机会。例如，任务负性和正性网络（DMN/SN）的连接变化已经被描述，但是在健康、无痛的个体中，持续有害刺激如何影响这些和其他连接网络，例如，调节下行疼痛控制的网络，仍然未知。
在 20 名健康志愿者中，我们在腹内侧前额叶皮层（vmPFC）、额前岛叶（rAI）、前扣带回皮质下亚区（ACC）和导水管周围灰质（PAG）进行持续冷痛刺激之前、期间和之后评估 FC。我们还使用计算机化视觉模拟量表记录主观报告的疼痛。
我们发现在疼痛刺激期间 DMN 的 FC 发生改变，并且 rAI 与 vmPFC 之间的网络间连接在疼痛期间增加，而 PAG-楔前叶的 FC 减少。在有害刺激之后，疼痛诱导的 FC 改变仍然存在。FC 改变与个体主观报告的疼痛程度有关。
我们在健康参与者中证明了在持续冷痛期间和之后 FC 的改变。我们的发现与慢性疼痛患者的报告相似，表明这些患者中观察到的一些 FC 改变可能与持续的传入伤害性驱动有关。
持续冷痛如何影响与疼痛相关的静息状态网络尚不清楚。我们在健康志愿者中研究了持续冷痛期间和之后的功能连接改变。冷痛干扰了腹内侧前额叶皮层、前岛叶和导水管周围灰质区域的功能连接。这些连接变化与个体报告的疼痛程度有关。我们认为，慢性疼痛患者中描述的一些连接变化可能是由于持续的传入外周驱动。
