Health Psychology, Faculty of Psychology and Educational Sciences, KU Leuven, Leuven, Belgium.
Institute of Neuroscience, UC Louvain, Brussels, Belgium.
Eur J Neurosci. 2019 Dec;50(12):3934-3943. doi: 10.1111/ejn.14546. Epub 2019 Sep 13.
Phasic pain stimuli are inhibited when they are applied concomitantly with a conditioning tonic stimulus at another body location (heterotopic noxious conditioning stimulation, HNCS). While the effects of HNCS are thought to rely on a spino-bulbo-spinal mechanism in animals (termed diffuse noxious inhibitory controls, DNIC), the underlying neurophysiology in humans may involve other pathways. In this study, we investigated the role of concomitant supraspinal mechanisms during HNCS by presenting auditory stimuli during a conditioning tonic painful stimulus (the cold pressor test, CPT). Considering that auditory stimuli are not conveyed through the spinal cord, any changes in brain responses to auditory stimuli during HNCS can be ascribed entirely to supraspinal mechanisms. Electroencephalography (EEG) was recorded during HNCS, and auditory stimuli were administered in three blocks, before, during and after HNCS. Nociceptive withdrawal reflexes (NWRs) were recorded at the same time points to investigate spinal processing. Our results showed that AEPs were significantly reduced during HNCS. Moreover, the amplitude of the NWR was significantly diminished during HNCS in most participants. Given that spinal and supraspinal mechanisms operate concomitantly during HNCS, the possibility of isolating their individual contributions in humans is questionable. We conclude that the net effects of HCNS are not independent from attentional/cognitive influences.
当在另一个身体部位同时施加相适应的紧张性刺激（异源性伤害性条件刺激，HNCS）时，阶段性疼痛刺激会受到抑制。虽然 HNCS 的作用被认为依赖于动物的脊髓-脑干-脊髓机制（称为弥散性伤害性抑制控制，DNIC），但其在人类中的潜在神经生理学机制可能涉及其他途径。在这项研究中，我们通过在紧张性疼痛刺激（冷加压试验，CPT）期间呈现听觉刺激，研究了 HNCS 期间伴随的中枢机制的作用。由于听觉刺激不通过脊髓传递，因此在 HNCS 期间，大脑对听觉刺激的反应的任何变化都可以完全归因于中枢机制。在 HNCS 期间记录了脑电图（EEG），并在 HNCS 之前、期间和之后的三个时间段内给予听觉刺激。在相同的时间点记录伤害性退缩反射（NWR），以研究脊髓处理。我们的结果表明，AEPs 在 HNCS 期间明显降低。此外，在大多数参与者中，HNCS 期间 NWR 的幅度明显减小。鉴于 HNCS 期间脊髓和中枢机制同时作用，在人类中分离它们各自贡献的可能性值得怀疑。我们得出结论，HCNS 的净效应与注意力/认知影响并非独立。
