The fungiform papilla as a multi-sensory end-organ

项目总结/摘要 我们对口中食物的感知是一种多模态的感官体验，包括味觉、嗅觉和嗅觉。 躯体感觉所有这些刺激联合收割机有助于食物的识别和适口性。第一 导致口腔中的“口腔感觉”的感知的步骤是外周躯体感觉的激活 神经元这些三叉神经体感神经元的多个类别支配口腔，并且可以是 由它们所响应的刺激类型来定义。例如，低阈值机械感受器（LTMR） 携带关于触摸或机械刺激的信息。在皮肤中，这些神经元中至少有7种明确的亚型 已经通过使用基因表达将这些神经元的解剖学特征与它们的 功能协调发展的我们不知道有多少专门的神经元亚型介导舌头的触觉， 它们特殊的解剖学和功能特性。了解食物引起的感觉 刺激需要我们确定每个LTMR亚型的独特解剖和功能特性， 舌头.同样重要的是，每个LTMR的活动如何与其他口腔感觉神经元类型整合 (i.e.味道和温度）。为了实现这些长期目标，我们建议使用两个遗传标识符， 检查支配菌状（味觉）乳头的三叉神经元亚型。我们的目标是专门测试 以下假设：1）味觉乳头由Aβ LTMR支配，具有小的感受野， 表达神经营养因子受体TrkC，并且它们的神经元可以进一步分为快速适应和 基于存在或不存在小清蛋白的缓慢适应型。2)这些Aβ LTMR投射到 脑干的一个区域，紧邻初级味觉终端区，它们在那里激活 对触摸有反应的突触后神经元。3)这些Aβ LTMR能够调节 在第一个味觉突触传递中品尝刺激。这些实验的成功完成确立了 菌状乳头作为机械感觉的终末器官，并提供了遗传工具，以探索的贡献， 在多模态食物刺激产生的感觉的整合中的LTMR的特定亚型。

Project Summary/Abstract 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 fields 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.