Animal studies have shown that high-frequency electrical stimulation (HFS) of peripheral C-fiber nociceptors induces both homo- and heterosynaptic long-term potentiation (LTP) within spinal nociceptive pathways. In humans, when HFS is applied onto the skin to activate nociceptors, single electrical stimuli are perceived more intense at the HFS site compared to a control site, a finding that was interpreted as a perceptual correlate of homosynaptic LTP. The present study aimed to investigate if after HFS the pain elicited by electrical stimuli delivered at the skin next to the HFS site is perceived as more intense compared to the pain at a control site (contralateral arm). To test this, HFS was applied to one of the two ventral forearms of twenty-four healthy participants. Before and after HFS, single electrical stimuli were delivered through the HFS electrode, through an identical electrode next to the HFS electrode and through an identical electrode at the contralateral arm. After HFS, the pain elicited by the single electrical stimuli was reduced at all three sites, with the largest reduction at the HFS site. Nevertheless, electrical stimuli delivered to the skin next to the HFS site were perceived as more intense than control stimuli. This result indicates that higher pain ratings to electrical stimuli after HFS at the HFS site cannot solely be interpreted as a perceptual correlate of homosynaptic changes. Furthermore, we show for the first time, in humans, that HFS can reduce pain elicited by single electrical stimuli delivered through the same electrode.

中文翻译：

---

皮肤伤害感受器的高频电刺激对同位和异位电刺激引起的疼痛感知有不同的影响。

动物研究表明，外周 C 纤维伤害感受器的高频电刺激 (HFS) 在脊髓伤害感受通路内诱导同型和异型突触长时程增强 (LTP)。在人类中，当将 HFS 应用到皮肤上以激活伤害感受器时，与对照部位相比，HFS 部位的单个电刺激感觉更强烈，这一发现被解释为同突触 LTP 的感知相关性。本研究旨在调查 HFS 后，与对照部位（对侧手臂）的疼痛相比，HFS 部位附近皮肤上的电刺激引起的疼痛是否被认为更强烈。为了测试这一点，将 HFS 应用于 24 名健康参与者的两个腹前臂之一。在 HFS 之前和之后，单个电刺激通过 HFS 电极、HFS 电极旁边的相同电极和对侧臂上的相同电极传递。HFS 后，单个电刺激引起的疼痛在所有三个部位均有所减轻，其中 HFS 部位减轻幅度最大。然而，传递到 HFS 部位旁边皮肤的电刺激被认为比控制刺激更强烈。该结果表明，HFS 部位 HFS 后对电刺激的较高疼痛等级不能单独解释为同突触变化的感知相关性。此外，我们首次在人类中表明，HFS 可以减轻通过同一电极传递的单个电刺激引起的疼痛。通过 HFS 电极旁边的相同电极和对侧臂上的相同电极。HFS 后，单个电刺激引起的疼痛在所有三个部位均有所减轻，其中 HFS 部位减轻幅度最大。然而，传递到 HFS 部位旁边皮肤的电刺激被认为比控制刺激更强烈。该结果表明，HFS 部位 HFS 后对电刺激的较高疼痛等级不能单独解释为同突触变化的感知相关性。此外，我们首次在人类中表明，HFS 可以减轻通过同一电极传递的单个电刺激引起的疼痛。通过 HFS 电极旁边的相同电极和对侧臂上的相同电极。HFS 后，单个电刺激引起的疼痛在所有三个部位均有所减轻，其中 HFS 部位减轻幅度最大。然而，传递到 HFS 部位旁边皮肤的电刺激被认为比控制刺激更强烈。该结果表明，HFS 部位 HFS 后对电刺激的较高疼痛等级不能单独解释为同突触变化的感知相关性。此外，我们首次在人类中表明，HFS 可以减轻通过同一电极传递的单个电刺激引起的疼痛。HFS 站点的降幅最大。然而，传递到 HFS 部位旁边皮肤的电刺激被认为比控制刺激更强烈。该结果表明，HFS 部位 HFS 后对电刺激的较高疼痛等级不能单独解释为同突触变化的感知相关性。此外，我们首次在人类中表明，HFS 可以减轻通过同一电极传递的单个电刺激引起的疼痛。HFS 站点的降幅最大。然而，传递到 HFS 部位旁边皮肤的电刺激被认为比控制刺激更强烈。该结果表明，HFS 部位 HFS 后对电刺激的较高疼痛等级不能单独解释为同突触变化的感知相关性。此外，我们首次在人类中表明，HFS 可以减轻通过同一电极传递的单个电刺激引起的疼痛。