Psychological Neuroscience Laboratory (PNL), Research Center in Psychology (CIPsi), School of Psychology, University of Minho, Braga, Portugal.
Psychological Neuroscience Laboratory (PNL), Research Center in Psychology (CIPsi), School of Psychology, University of Minho, Braga, Portugal.
Brain Res. 2025 Jan 1;1846:149267. doi: 10.1016/j.brainres.2024.149267. Epub 2024 Oct 5.
Affective touch is mediated by specialized receptors sensitive to gentle and slow touch called C-tactile afferents (CT). The activation of these receptors has shown promise in reducing subjective pain ratings, however, how this type of touch can affect central sensitization processes is poorly studied. This work aimed to investigate if affective touch is able to modulate pain sensitization and its electrophysiological correlates during Temporal Summation of Second Pain (TSSP), a phenomenon characterized by an increase in pain perception due to repeated noxious stimuli. Thirty-seven participants underwent a TSSP protocol involving three conditions: TSSP alone, TSSP during vibrotactile stimulation, and TSSP during CT stimulation (administered with a brush mounted in a robot arm). We measured subjective pain ratings, electroencephalographic (N2-P2 complex) and electrocardiographic activity during these conditions. Participants reported a significantly lower increase of pain during CT stimulation compared to vibrotactile stimulation, but not to TSSP alone. In addition, TSSP was reduced when administered in the ipsilateral arm compared to the other somatosensory stimulation. Subjective reports of attention towards painful stimuli, amplitude of the N2-P2 complex, and heart rate were also reduced during CT stimulation. Conclusion: Our results indicated that the activation of CT receptors may reduce sensitization compared to other types of somatosensory stimulation, which is possibly related to the reduction of the attention devoted to nociceptive stimulation. Our results suggest that activation of CT receptors may alleviate the occurrence of central pain sensitization.
情感触觉是由对轻柔缓慢触摸敏感的专门受体介导的，称为 C 型触觉传入纤维（CT）。这些受体的激活已被证明可以降低主观疼痛评分，然而，这种类型的触摸如何影响中枢敏化过程的研究还很少。本研究旨在探讨情感触觉是否能够调节 TSSP 期间的疼痛敏化及其电生理相关性，TSSP 是一种由于重复的有害刺激而导致疼痛感知增加的现象。37 名参与者接受了 TSSP 方案，包括三种条件：单独 TSSP、TSSP 期间的振动触觉刺激和 TSSP 期间的 CT 刺激（使用安装在机器人臂上的刷子进行）。我们在这些条件下测量了主观疼痛评分、脑电图（N2-P2 复合体）和心电图活动。与振动触觉刺激相比，参与者报告在 CT 刺激期间疼痛增加明显减少，但与单独的 TSSP 相比则没有。此外，当在同侧手臂给予 TSSP 时，其强度比其他躯体感觉刺激要小。在 CT 刺激期间，对疼痛刺激的注意力、N2-P2 复合体的振幅和心率也降低。结论：我们的结果表明，与其他类型的躯体感觉刺激相比，CT 受体的激活可能会减轻敏化，这可能与对伤害性刺激的注意力减少有关。我们的结果表明，CT 受体的激活可能会减轻中枢疼痛敏化的发生。
