TASTE PSYCHOPHYSICS

（作者摘要）本研究的长期目标是了解味觉的遗传和病理变异对健康和生活质量的影响。人类在味觉上表现出基因变异。这种变化的特点是真菌状乳头（容纳味蕾的结构）的数量和品尝PROP （6-n-丙基硫尿嘧啶）苦味的能力。因为真菌状乳头接受味觉、疼痛和触觉神经元的神经支配，那些拥有最多乳头的人（即超味觉者）能感知更强烈的味觉、口腔灼烧感（如辣椒）和口腔触觉（如脂肪）。基因味觉变异与对苦味食物的厌恶和对甜味和甜味食物的偏好有关（这包括水果和蔬菜，这些食物是心血管疾病和癌症的重要媒介）。味觉基因变异也与酗酒和吸烟有关。涉及鼓室索神经的病理与口腔幻觉（缺乏刺激的感觉）有关；这些症状出现在味觉障碍和口腔疼痛（灼口综合征）。所评估的假设是鼓室索神经（味觉，舌前）通常抑制舌咽神经（味觉，舌后）和三叉神经（疼痛，舌前）。因此，对鼓室索的损伤会释放这种抑制，导致味觉和疼痛感觉增强，以及易感个体的幻觉（例如，诵读困难，灼口综合征）。易受影响的个体似乎是那些拥有最密集的味觉和疼痛神经的人（即超味觉者）。该方案包括心理物理和解剖学实验。其中一组实验将使用心理物理方法和味觉解剖学的最新进展来确定味觉味觉者、中等味觉者和超级味觉者之间的口腔感官差异程度。另外的实验将测试对味觉和口腔灼烧的抑制释放的假设。正常人的鼓室索会被麻醉。患者包括听神经瘤患者，他们的鼓室索必须通过手术从其细胞体的中央切断；神经将从切口退化到大脑可能导致中枢重组。患者还包括那些乳突切除术或镫骨切除术的患者，他们的鼓室索必须被切断到细胞体周围；神经会从伤口退化到舌头可能会改变周围的解剖结构。最后一类患者是那些有味觉和/或口腔疼痛幻觉的患者；他们将被评估是否有可能损伤鼓室索神经。

DESCRIPTION: (Author's Abstract) The long-term goal of this research is to understand the influence of genetic and pathological variation in taste sensations on health and quality of life. Humans show genetic variation in taste. This variation is characterized by the number of fungiform papillae (structures that house taste buds) and the ability to taste the bitterness of PROP (6-n-propylthiouracil). Because the fungiform papillae receive innervation from taste, pain, and touch neurons, those who have the highest number of papillae (i.e., supertasters) perceive more intense taste, oral burn (e.g., chilis) and oral touch (e.g., fat) sensations. Genetic taste variation is linked to distaste for bitter foods and preference for sweet and far foods (this includes fruits and vegetables, foods that are important mediators of cardiovascular disease and cancer). Genetic taste variation is also linked to alcoholism and smoking. Pathologies involving the chorda tympani nerve are linked to oral phantoms (sensations in the absence of stimulation); these occur for taste (dysgeusia) and oral pain (burning mouth syndrome). The hypothesis under evaluation is that the chorda tympani nerve (taste, anterior tongue) normally inhibits the glossopharyngeal nerve (taste, posterior tongue) and the trigeminal nerve (pain, anterior tongue). Damage to the chorda tympani thus releases that inhibition leading to intensified taste and pain sensations as well as phantoms (e.g., dysgeusia, burning mouth syndrome) in susceptible individuals. Susceptible individuals appear to be those who have the densest taste and pain innervation (i.e., supertasters). The proposal includes psychophysical and anatomical experiments. One group of experiments will use recent advances in psychophysical methodology and taste anatomy to determine the magnitude of oral sensory differences across nontasters, medium tasters and supertasters. Additional experiments will test the hypothesized release of inhibition on taste and oral burn. The chorda tympani will be anesthetized in normal volunteers. Patients will include those with acoustic neuromas in whom the chorda tympani must necessarily be surgically severed central to its cell bodies; the nerve will degenerate from the cut into the brain possibly leading to central reorganization. Patients will also include those with mastoidectomies or stapedectomies in whom the chorda tympani must necessarily be severed peripheral to the cell bodies; the nerve will degenerate from the cut into the tongue possibly altering peripheral anatomy. A final group of patients are those with taste and/or oral pain phantoms; they will be evaluated for possible damage to the chorda tympani nerve.