Pain is an integrated sensory and affective experience. Cortical mechanisms of sensory and affective integration, however, remain poorly defined. Here, we investigate the projection from the primary somatosensory cortex (S1), which encodes the sensory pain information, to the anterior cingulate cortex (ACC), a key area for processing pain affect, in freely behaving rats. By using a combination of optogenetics, in vivo electrophysiology, and machine learning analysis, we find that a subset of neurons in the ACC receives S1 inputs, and activation of the S1 axon terminals increases the response to noxious stimuli in ACC neurons. Chronic pain enhances this cortico-cortical connection, as manifested by an increased number of ACC neurons that respond to S1 inputs and the magnified contribution of these neurons to the nociceptive response in the ACC. Furthermore, modulation of this S1→ACC projection regulates aversive responses to pain. Our results thus define a cortical circuit that plays a potentially important role in integrating sensory and affective pain signals.

中文翻译：

---

映射感觉和情感疼痛通路的皮层整合。

疼痛是一种综合的感官和情感体验。然而，感觉和情感整合的皮层机制仍然不明确。在这里，我们研究了从编码感觉疼痛信息的初级躯体感觉皮层 (S1) 到前扣带皮层 (ACC)（处理疼痛影响的关键区域）在行为自由的大鼠中的投射。通过结合使用光遗传学、体内电生理学和机器学习分析，我们发现 ACC 中的一部分神经元接收 S1 输入，并且 S1 轴突末端的激活增加了 ACC 神经元对有害刺激的反应。慢性疼痛增强了这种皮质 - 皮质连接，表现为响应 S1 输入的 ACC 神经元数量增加以及这些神经元对 ACC 中伤害性反应的贡献被放大。此外，这种 S1→ACC 投射的调节调节了对疼痛的厌恶反应。因此，我们的结果定义了一个皮质回路，它在整合感觉和情感疼痛信号方面发挥着潜在的重要作用。