Nucleus of Neuroscience and Behavior and Nucleus of Applied Neuroscience, Universidade de São Paulo, São Paulo, Brazil.
Research, Technology, and Data Science Unit, Projeto Superador, São Paulo, Brazil.
Pain. 2020 Oct;161(10):2321-2329. doi: 10.1097/j.pain.0000000000001919.
Experimental data suggest that associative learning can influence defensive avoidance behavior and pain perception in humans. However, whether voluntary movements can become conditioned stimuli (CSs) and influence pain responses is yet to be evaluated. Forty healthy volunteers participated in this study. Electrocutaneous stimuli applied to the shoulder at pain threshold level (US) and at pain tolerance level (US) were determined before a movement-conditioning paradigm. First, reaching movements to visual cues shown on one side of a computer screen were associated with the US (CS+ movements) on 80% of trials, whereas reaching movements to visual stimuli shown on the other side were never associated with the nociceptive-US (CS- movements). Next, participants underwent a test phase in which movements to visual cues on both sides were paired with the US on 50% of trials. During the test phase, participants were asked to evaluate whether the movement was painful (yes/no) and to rate pain intensity after each trial. Movement onset and duration as well as skin conductance responses were collected. The US stimuli were more likely to be perceived as painful and were also rated as more painful during CS+ movements. Movement onset latency and skin conductance responses were significantly higher in anticipation of the CS+ movement as compared to the CS- movement. These findings suggest that pain can be conditioned to voluntary movements.
实验数据表明，联想学习可以影响人类的防御性回避行为和疼痛感知。然而，自愿运动是否可以成为条件刺激（CS）并影响疼痛反应，尚待评估。
这项研究共有 40 名健康志愿者参加。在运动条件作用范式之前，确定了施加于肩部痛阈水平（US）和痛耐受水平（US）的电皮肤刺激。首先，在计算机屏幕一侧显示视觉线索的伸手运动与 US（CS+运动）相关联，在 80%的试验中，而在另一侧显示视觉刺激的伸手运动从不与伤害性-US（CS-运动）相关联。接下来，参与者进行了测试阶段，在该阶段，将视觉线索的运动与 50%的试验中的 US 配对。在测试阶段，要求参与者评估运动是否疼痛（是/否），并在每次试验后评估疼痛强度。收集运动起始和持续时间以及皮肤电反应。与 CS-运动相比，CS+运动中 US 刺激更有可能被感知为疼痛，并且也被评为更疼痛。与 CS-运动相比，CS+运动的运动起始潜伏期和皮肤电反应显著更高。这些发现表明疼痛可以被条件化到自愿运动中。
