Kludt Eugen, Okom Camille, Brinkmann Alexander, Schild Detlev
Institute of Neurophysiology and Cellular Biophysics, University of Göttingen, 37073 Göttingen, Germany, Bernstein Center for Computational Neuroscience, 37073 Göttingen, Germany.
Institute of Neurophysiology and Cellular Biophysics, University of Göttingen, 37073 Göttingen, Germany, Center for Nanoscale Microscopy and Molecular Physiology of the Brain, Georg-August-Universität Göttingen, 37073 Göttingen, Germany.
J Neurosci. 2015 May 20;35(20):7892-902. doi: 10.1523/JNEUROSCI.0571-15.2015.
Temperature perception has long been classified as a somesthetic function solely. However, in recent years several studies brought evidence that temperature perception also takes place in the olfactory system of rodents. Temperature has been described as an effective stimulus for sensory neurons of the Grueneberg ganglion located at the entrance of the nose. Here, we investigate whether a neuronal trace of temperature stimulation can be observed in the glomeruli and mitral cells of the olfactory bulb, using calcium imaging and fast line-scanning microscopy. We show in the Xenopus tadpole system that the γ-glomerulus, which receives input from olfactory neurons, is highly sensitive to temperature drops at the olfactory epithelium. We observed that thermo-induced activity in the γ-glomerulus is conveyed to the mitral cells innervating this specific neuropil. Surprisingly, a substantial number of thermosensitive mitral cells were also chemosensitive. Moreover, we report another unique feature of the γ-glomerulus: it receives ipsilateral and contralateral afferents. The latter fibers pass through the contralateral bulb, cross the anterior commissure, and then run to the ipsilateral olfactory bulb, where they target the γ-glomerulus. Temperature drops at the contralateral olfactory epithelium also induced responses in the γ-glomerulus and in mitral cells. Temperature thus appears to be a relevant physiological input to the Xenopus olfactory system. Each olfactory bulb integrates and codes temperature signals originating from receptor neurons of the ipsilateral and contralateral nasal cavities. Finally, temperature and chemical information is processed in shared cellular networks.
长期以来，温度感知一直仅被归类为一种躯体感觉功能。然而，近年来的几项研究表明，啮齿动物的嗅觉系统中也存在温度感知。温度已被描述为位于鼻腔入口处的格伦贝格神经节感觉神经元的有效刺激物。在此，我们使用钙成像和快速线扫描显微镜，研究在嗅球的肾小球和二尖瓣细胞中是否能观察到温度刺激的神经元痕迹。我们在非洲爪蟾蝌蚪系统中发现，接收嗅觉神经元输入的γ - 肾小球对嗅上皮的温度下降高度敏感。我们观察到，γ - 肾小球中的热诱导活动会传递到支配这个特定神经纤维网的二尖瓣细胞。令人惊讶的是，大量对温度敏感的二尖瓣细胞对化学物质也敏感。此外，我们报告了γ - 肾小球的另一个独特特征：它接收同侧和对侧传入纤维。后者的纤维穿过对侧嗅球，穿过前连合，然后跑到同侧嗅球，在那里它们靶向γ - 肾小球。对侧嗅上皮的温度下降也会在γ - 肾小球和二尖瓣细胞中引发反应。因此，温度似乎是非洲爪蟾嗅觉系统的一种相关生理输入。每个嗅球整合并编码来自同侧和对侧鼻腔受体神经元的温度信号。最后，温度和化学信息在共享的细胞网络中进行处理。
