Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), Berlin, Germany.
Neuroscience Research Center, Charité-Universitätsmedizin Berlin, Berlin, Germany.
Nature. 2023 Feb;614(7949):725-731. doi: 10.1038/s41586-023-05705-5. Epub 2023 Feb 8.
Temperature is a fundamental sensory modality separate from touch, with dedicated receptor channels and primary afferent neurons for cool and warm. Unlike for other modalities, however, the cortical encoding of temperature remains unknown, with very few cortical neurons reported that respond to non-painful temperature, and the presence of a 'thermal cortex' is debated. Here, using widefield and two-photon calcium imaging in the mouse forepaw system, we identify cortical neurons that respond to cooling and/or warming with distinct spatial and temporal response properties. We observed a representation of cool, but not warm, in the primary somatosensory cortex, but cool and warm in the posterior insular cortex (pIC). The representation of thermal information in pIC is robust and somatotopically arranged, and reversible manipulations show a profound impact on thermal perception. Despite being positioned along the same one-dimensional sensory axis, the encoding of cool and that of warm are distinct, both in highly and broadly tuned neurons. Together, our results show that pIC contains the primary cortical representation of skin temperature and may help explain how the thermal system generates sensations of cool and warm.
温度是一种独立于触觉的基本感觉模态，具有专门的冷和温受体通道和初级传入神经元。然而，与其他模态不同的是，温度的皮质编码仍然未知，只有极少数皮质神经元被报道对非疼痛温度有反应，而且“热皮质”的存在也存在争议。在这里，我们使用小鼠前爪系统中的宽场和双光子钙成像技术，鉴定出对冷却和/或加热具有不同空间和时间反应特性的皮质神经元。我们观察到初级体感皮层中对冷的反应，但对温暖的反应不存在，而在后岛叶皮层（pIC）中则存在。pIC 中热信息的表示是稳健的，并且具有躯体感觉排列，可逆性操作显示对热感觉有深远的影响。尽管位于同一一维感觉轴上，但冷和温暖的编码是不同的，在高度和广泛调谐的神经元中都是如此。总之，我们的结果表明，pIC 包含皮肤温度的主要皮质代表，可能有助于解释热系统如何产生冷和温暖的感觉。
