Rodents and human studies indicate that the hippocampus, a brain region necessary for memory processing, responds to noxious stimuli. However, the hippocampus has yet to be considered a key brain region directly involved in the human pain experience. One approach to answer this question is to perform quantitative sensory testing on patients with hippocampal damage-ie, medial temporal lobe epilepsy. Some case studies and case series have performed such tests in a handful of patients with various types of epilepsy and have reported mixed results. Here, we aimed to determine whether mechanical pain sensitivity was altered in patients diagnosed with temporal lobe epilepsy. We first investigated whether mechanical pain sensitivity in patients with temporal lobe epilepsy differs from that of healthy individuals. Next, in patients with temporal lobe epilepsy, we evaluated whether the degree of pain sensitivity is associated with the degree of hippocampal integrity. Structural integrity was based on hippocampal volume, and functional integrity was based on verbal and visuospatial memory scores. Our findings show that patients with temporal lobe epilepsy have lower mechanical pain sensitivity than healthy individuals. Only left hippocampal volume was positively associated with mechanical pain sensitivity-the greater the hippocampal damage, the lower the sensitivity to mechanical pain. Hippocampal measures of functional integrity were not significantly associated with mechanical pain sensitivity, suggesting that the mechanisms of hippocampal pain processing may be different than its memory functions. Future studies are necessary to determine the mechanisms of pain processing in the hippocampus.

中文翻译：

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机械疼痛敏感性与海马结构完整性相关。

啮齿动物和人类研究表明，海马体是记忆处理所必需的大脑区域，会对有害刺激做出反应。然而，海马体尚未被认为是直接参与人类疼痛体验的关键大脑区域。回答这个问题的一种方法是对海马损伤（即内侧颞叶癫痫）的患者进行定量感觉测试。一些案例研究和案例系列对少数患有各种类型癫痫的患者进行了此类测试，并报告了不同的结果。在这里，我们的目的是确定诊断为颞叶癫痫的患者机械疼痛敏感性是否改变。我们首先研究了颞叶癫痫患者的机械疼痛敏感性是否与健康个体不同。接下来，在颞叶癫痫患者中，我们评估了疼痛敏感性程度是否与海马完整性程度相关。结构完整性基于海马体积，功能完整性基于言语和视觉空间记忆评分。我们的研究结果表明，颞叶癫痫患者的机械疼痛敏感性低于健康人。只有左侧海马体积与机械性疼痛敏感性呈正相关——海马损伤越大，对机械性疼痛的敏感性越低。海马功能完整性的测量与机械疼痛敏感性没有显着相关，这表明海马疼痛处理机制可能与其记忆功能不同。未来的研究有必要确定海马体疼痛处理的机制。