The fungiform papilla as a multi-sensory end-organ

项目摘要/摘要 我们对食物在嘴里的感知是一种多模式的感官体验，包括味觉、嗅觉和 体感。所有这些刺激结合在一起，有助于识别和品尝食物。第一 在口腔中感觉“口感”的步骤是激活外周躯体感觉 神经元。这些三叉神经体感神经元的多种类型支配口腔，并且可以 由它们对刺激做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。在皮肤中，这些神经元至少有7个明显的亚型 通过使用基因表达将这些神经元的解剖特征与它们的 功能。我们不知道有多少专门的神经元亚型在舌头或 它们的特殊解剖和功能特性。理解食物引起的感觉 刺激需要我们确定每个LTMR亚型在大脑中的独特解剖和功能特性 舌头。同样重要的是，每个LTMR的活动如何与其他类型的口腔感觉神经元相结合 (即味道和温度)。为了实现这些长期目标，我们建议使用两个遗传识别符 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AβLTMR支配，它具有一个小的接受野， 表达神经营养因子受体TrkC，并将它们的神经元进一步分为快速适应和 根据小白蛋白的存在或不存在缓慢适应类型。2)这些AβLTM项目到TO 脑干的一个区域，紧邻初级味觉终端场，在那里它们被激活 对触摸有反应的突触后神经元。3)这些AβLTM能够调制响应 在第一次味觉突触接力时品尝刺激。这些实验的成功完成奠定了 菌状乳头作为机械感官的末端器官，并提供了遗传学工具来探索 LTMR的一个特定亚型，整合了由多模式食物刺激产生的感觉。

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.