The fungiform papilla as a multi-sensory end-organ

项目总结/家长资助。我们对口中食物的感知是一种多模式的感官体验 包括味觉、嗅觉和躯体感觉。所有这些刺激结合在一起有助于识别和 食物的适口性。在口腔中产生“口感”感觉的第一步是激活 外周体感神经元。这些三叉神经体感神经元的多个类别支配 口腔，可由它们对刺激作出反应的类型来定义。例如，低阈值 机械感受器(LTMR)携带有关触摸或机械刺激的信息。在皮肤上，至少7个透明 这些神经元的亚型是通过使用基因表达来关联 这些神经元及其功能。我们不知道有多少专门的神经元亚型调节触摸 舌头上的感觉或其特殊的解剖和功能特性。理解这种感觉 由食物刺激引起的刺激需要我们确定每种食物独特的解剖和功能特性 舌中LTMR亚型。同样重要的是，每个LTMR的活动如何与其他口头活动相结合 感觉神经元类型(即味觉和温度)。对于这些长期目标，我们建议使用两个 用于检查支配菌状(味觉)乳头的三叉神经细胞亚型的遗传识别符。我们的目标 具体检验以下假设：1)味觉乳头是由AβLTM支配的 表达神经营养素受体TrkC的感受野，它们的神经元可以进一步分为 基于有无小白蛋白的快速适应和缓慢适应类型。2)这些Aβ LTMR投射到脑干上紧邻初级味觉终末区域的区域 在那里，它们激活对触摸有反应的突触后神经元。3)这些AβLTM能够 在第一次味觉突触传递中调制对味觉刺激的反应。成功完成这些任务 实验建立了菌状乳头作为机械感觉的末端器官，并提供了遗传工具 为了探索LTMR的一个特定亚型在多个刺激产生的感觉整合中的贡献。 模式化食物刺激。

Project Summary/Parent grant. Our perception of food in the mouth is a multi-modal sensory experience involving taste, olfaction, and somatosensation. All of these stimuli combine to contribute to the recognition and palatability of food. The first step leading to the perception of ‘mouth feel” in the oral cavity is activation of peripheral somatosensory neurons. Multiple classes of these trigeminal somatosensory neurons innervate the oral cavity and can be defined by the types of stimuli to which they respond. For example, low threshold mechanoreceptors (LTMRs) carry information concerning touch or mechanical stimuli. In skin, at least 7 clear subtypes of these neurons have been defined by using gene expression to relate the anatomical features of these neurons with their functions. We do not know how many specialized neuron subtypes mediate touch sensation in the tongue or their specialized anatomical and functional properties. Understanding the sensations evoked by a food stimulus requires us to determine the unique anatomical and functional properties of each LTMR subtype in the tongue. Equally important is how each LTMR’s activities are integrated with other oral sensory neuron types (i.e. taste and temperature). Toward these long-term goals we propose to use two genetic identifiers to examine trigeminal neuron subtypes innervating the fungiform (taste) papillae. Our Aims specifically test the following hypotheses: 1) Taste papillae are innervated by a Aβ LTMRs with a small receptive field that express the neurotrophin receptor, TrkC, and that they neurons can further be divided into rapidly adapting and slowly-adapting types based on the presence or absence of Parvalbumin. 2) These Aβ LTMRs project to the to a region of the brainstem immediately adjacent to the primary taste terminal field where they activate postsynaptic neurons that are responsive to touch. 3) These Aβ LTMRs are capable of modulating responses to taste stimuli at the first gustatory synaptic relay. Successful completion of these experiments establishes the fungiform papilla as a mechanosensory end organ and provides the genetic tools to explore the contribution of a specific subtype of LTMR in the integration of sensations produced by the multi- modal food stimulus.