Oral Somesthesis and Taste

该项目的长期目标是了解躯体感觉和味觉系统如何共同作用以产生口腔感觉和味道。这一目标将通过利用最近的三个心理物理学发现来实现，这些发现为躯体感觉刺激如何影响味觉提供了新的见解。首先，研究将对热味觉现象进行调查，其中味觉可以由温度单独诱导。特别感兴趣的是热味觉的个体和空间变化的来源，热味觉和化学味觉之间的相互作用，以及热味觉的空间和时间特征，因为它们与温暖和寒冷的敏感性有关。其次，将研究由舌头前部短暂的冷刺激引起的“幻味”的诱导和感知。这些冷致幻像（cip）是在冷刺激之后而不是在冷刺激过程中被感知的，并且是在远离冷却部位而不是在冷却部位。当口腔感觉系统内部和之间假定的强直性抑制被冷阻滞中断时，提出了实验来验证cip的假设，该假设可逆地模拟了临床发音障碍。第三，初步观察表明，辣椒素作为典型的“三叉神经”刺激物，可以在舌头的环戊酸区引起明显的苦味，并且那里的感官刺激和温暖感知都比舌尖弱得多。实验将研究一些舌咽部神经元对刺激物敏感的可能性，更一般地说，某些感觉和味觉之间的关系在舌头后部是不同的，在那里两种刺激都是由舌咽部神经单独介导的。总的来说，这些研究将促进我们对人类口腔感觉处理的理解，并提供有关感觉相互作用的数据，这可能有助于理解某些类型的口腔感觉病理（例如，听力障碍）的来源。

The long-term goal of this project is to understand how the somesthetic and gustatory systems function together to produce oral sensations and flavors This goal will be pursued by taking advantage of three recent psychophysical findings that provide novel insights into how somatosensory stimulation can influence taste. First, studies will be conducted to investigate the phenomenon of thermal taste, in which tastes can be induced by temperature alone. Of particular interest are sources of individual and spatial variation in thermal taste, interactions between thermal taste and chemical taste, and the spatial and temporal characteristics of thermal tastes as they relate to the sensitivity to warmth and cold. Second, the induction and perception of 'phantom' tastes caused by brief bouts of cold stimulation on the front of the tongue will be investigated. These cold-induced phantoms (CIPs) are perceived after rather than during cold stimulation, and are localized away from rather than at the site of cooling. Experiments are proposed to test the hypothesis that CIPs, which reversibly mimic clinical dysgeusias, arise when putative tonic inhibition within and between oral sensory systems is interrupted by cold-block. Third, preliminary observations indicate that capsaicin, the prototypical "trigeminal" irritant, can evoke significant bitterness in the circumvallate region of the tongue, and that both sensory irritation and perception of warmth are much weaker there than on the tongue tip. Experiments will investigate the possibility that some glossopharyngeal neurons that contribute to perception of bitterness are sensitive to irritants, and more generally, that the relationship between somesthesis and taste is different on the back of the tongue, where both kinds of stimulation are mediated solely by the glossopharyngeal nerve. Overall, these studies will advance our understanding of oral sensory processing in humans as well as provide data on sensory interactions that may be helpful in understanding the source of certain types of oral sensory pathologies (e.g., dysgeusias).