Department of Biologic and Materials Sciences, School of Dentistry, University of Michigan, Ann Arbor, MI 48109-1078, United States.
Department of Biologic and Materials Sciences, School of Dentistry, University of Michigan, Ann Arbor, MI 48109-1078, United States; Department of Molecular and Integrative Physiology, Medical School, University of Michigan, Ann Arbor, MI 48109-0622, United States.
Neuroscience. 2017 Dec 26;367:147-158. doi: 10.1016/j.neuroscience.2017.10.032. Epub 2017 Oct 31.
Afferent chorda tympani (CT) fibers innervating anterior tongue fungiform papillae have neuron cell bodies in the geniculate ganglion (GG). To characterize electrophysiological and receptive field properties, we recorded extracellular responses from single GG neurons to lingual application with chemical, thermal and mechanical stimuli. Receptive field size was mapped by electrical stimulation of individual fungiform papillae. Responses of GG neurons to room temperature chemical stimuli representing five taste qualities, and distilled water at 4 °C and mechanical stimulation were used. Based on responses to these stimuli, GG neurons were divided into CHEMICAL, CHEMICAL/THERMAL, THERMAL and TACTILE groups. Neurons in the CHEMICAL group responded to taste stimuli but not to either cold water or stroking stimuli. CHEMICAL/THERMAL neurons responded to both taste stimuli and cold water. THERMAL neurons responded only to cold water and TACTILE neurons responded only to light stroking stimuli. The receptive field sizes for CHEMICAL, and CHEMICAL/THERMAL neurons averaged five papillae exceeding the field size of THERMAL and TACTILE neurons which averaged about two papillae. Detailed analysis of the receptive field of CHEMICAL/THERMAL neurons revealed that within one field only a subset of the fungiform papillae making up the receptive field responded to the cold stimuli, whereas the other papillae responded only to chemical stimuli. These finding demonstrate that fungiform papilla are complex sensory organs with a multisensory function suggesting a unique role in detecting and sampling food components prior to ingestion.
传入鼓索（CT）纤维支配前舌菌状乳头的神经元胞体位于膝状神经节（GG）中。为了描述传入 GG 神经元的电生理和感受野特性，我们记录了对舌部应用化学、热和机械刺激时单个 GG 神经元的细胞外反应。通过对单个菌状乳头的电刺激来绘制感受野大小。使用代表五种味觉的室温化学刺激物（蒸馏水 4°C 和机械刺激）对 GG 神经元进行了测试。根据这些刺激的反应，GG 神经元分为化学、化学/热、热和触觉组。化学组神经元对味觉刺激有反应，但对冷水或轻触刺激无反应。化学/热神经元对味觉刺激和冷水都有反应。热神经元仅对冷水有反应，触觉神经元仅对轻触刺激有反应。化学和化学/热神经元的感受野大小平均为五个乳头，超过了热和触觉神经元的感受野大小，后者平均约为两个乳头。对化学/热神经元感受野的详细分析表明，在一个感受野中，仅有一部分组成感受野的菌状乳头对冷刺激有反应，而其他乳头仅对化学刺激有反应。这些发现表明，菌状乳头是具有多感觉功能的复杂感觉器官，这表明它们在摄入前检测和采样食物成分方面具有独特的作用。
