Cognitive and affective influences on taste processing

描述(由申请人提供)：众所周知，由于味觉感受器或其他外周味觉生理学的遗传变异，味觉强度感知存在个体差异[1-8]。更少被探索的是其他来源的可能性 可变性。在先前项目期间的新证据的指导下，味觉系统是一个综合的口腔感觉系统，表现出瞬时和长期的可塑性，拟议的工作将结合人类的心理物理学和神经成像方法来研究影响味觉敏感性的中枢和外周神经机制。在……里面 目的1我们将检验中枢获得机制在人类味觉个体差异中起重要作用的假说。虽然对敏感度差异的外围解释通常是针对特定质量或化学物质的，但我们建议开发和验证一个确定整体味觉系统敏感度的大脑回路的神经生物学模型。在目标2中，我们将研究长时间对口腔而不是口外感觉的定向注意是否通过调节前脑岛或所提出的中枢获得机制来提高味觉和味道敏感度。在这个项目的第一阶段，我们确定了一个更高阶的皮质网络，它调节味觉皮质的处理，为目标定向行为服务[9-12]。新的飞行员数据表明，从事一项需要长时间注意的心理物理任务可能会调节这种机制。我们将通过比较味觉回路中味觉强度的变化和味觉回路中的血氧水平依赖(BOLD)反应来检验这一假设，这些反应在需要直接注意味道和视觉刺激的任务之前和之后。在目标3中，我们调查饮食对味觉敏感性的影响的可能性。关于食用人工甜味剂(AFS)导致体重增加的可能性，存在重大争议。一些研究发现AFS的使用与体重增加和/或糖尿病相关[13-16]，而另一些研究表明AFSS可能有助于减肥[17]或对身体质量指数(BMI)没有影响[18]。鉴于FDA批准的五种AFSS存在于数千种食品中[19]，这标志着人们在认识上存在明显而显著的差距。我们的初步数据显示，在饮用了两包斯普伦达甜味饮料仅10天后，甜味敏感度就下降了3倍。这些数据提供了强有力的证据，表明反复暴露于三氯蔗糖可以降低人们对甜味强度的感知，这很可能是通过下调甜味受体来实现的。总体而言，确定中心 除了与获得调节和定向注意相关的味觉调节机制，以及食用AFS可能触发的外围机制外，拟议的工作将促进对与食物选择和消费相关的个体味觉差异来源的理解。

DESCRIPTION (provided by applicant): It is well established that there are individual differences in taste intensity perception resulting from genetic variation in taste receptors or other peripheral taste physiology [1-8]. Much less explored is the possibility for other sources of variability. Guided by new evidence from the prior project period which indicates that the gustatory system is an integrated oral sensory system that exhibits both transient and long-term plasticity, the proposed work will combine psychophysics and neuroimaging methods in humans to investigate central as well as peripheral neural mechanisms that influence taste sensitivity. In aim 1 we will test the hypothesis that a central gain mechanism plays a significant role in individual differences in taste perception in humans. Whereas peripheral explanations of variance in sensitivity are often specific to a particular quality or chemical, we propose to develop and validate a neurobiological model of brain circuitry that determines overall taste system sensitivity. In aim 2 we will investigate whether prolonged directed attention to oral but not extra-oral sensations increases taste and flavor sensitivity via modulation of the anterior insula or the proposed central gain mechanism. In the first period of this project we identified a higher-order cortical network that modulates processing in gustatory cortex in the service of goal directed behaviors [9-12]. New pilot data suggests that engaging in a psychophysical task that demands prolonged attention may modulate this mechanism. We will test this hypothesis by comparing changes in taste intensity and the blood oxygen level dependent (BOLD) responses in gustatory circuits before and after tasks requiring directed attention to flavors vs. visual stimuli. In aim 3 we investigate the possibility of a dietary influence on gustatory sensitivity. Significant controversy surrounds the possibility that consumption of artificial sweeteners (AFS) leads to weight gain. Some studies have found correlations between AFS use and weight gain and/or diabetes [13-16] while others have indicated that AFSs may aid in weight loss [17] or have no effects on body mass index (BMI) [18]. Given that the five FDA approved AFSs are found in thousands of foods [19] this marks a clear and significant gap in knowledge. Our preliminary data demonstrate a 3-fold decrease in sweet taste sensitivity following consumption of a beverage sweetened with two packets of Splenda for just 10 days. These data provide strong evidence that repeated exposure to sucralose reduces perception of sweet taste intensity, most likely by down regulation of the sweet taste receptor. Overall, identifying central mechanisms of taste modulation related to gain modulation and directed attention, as well as a possible peripheral mechanism triggered by consumption of an AFS, the proposed work will advance understanding of sources of individual differences in taste that are relevant to food choice and consumption.