Cognitive and affective influences on taste processing

描述（由申请人提供）：众所周知，味觉感受器或其他外周味觉生理学的遗传变异导致味觉强度感知存在个体差异[1-8]。更少探索的是其他来源的可能性， 可变性从先前的项目期间，这表明味觉系统是一个综合的口腔感觉系统，表现出短暂的和长期的可塑性的新证据的指导下，拟议的工作将联合收割机结合心理物理学和神经成像方法在人类调查中央以及周围神经机制，影响味觉敏感性。在 目的1我们将检验中枢增益机制在人类味觉的个体差异中起重要作用的假设。而周边解释的敏感性的变化往往是特定的质量或化学品，我们建议开发和验证的神经生物学模型的大脑回路，确定整体味觉系统的敏感性。在目标2中，我们将研究是否长期直接注意口腔而不是口外的感觉增加味觉和风味的敏感性，通过调制的前额叶或建议的中央增益机制。在这个项目的第一阶段，我们确定了一个高阶皮层网络，它调节味觉皮层中的处理，为目标导向行为服务[9-12]。新的试验数据表明，从事一项需要长时间注意力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和血氧水平依赖性（BOLD）反应的变化来测试这一假设，这些反应在需要直接注意味道与视觉刺激的任务之前和之后。在目标3中，我们研究了饮食对味觉敏感性的影响。关于食用人造甜味剂（AFS）导致体重增加的可能性存在重大争议。一些研究发现AFS使用与体重增加和/或糖尿病之间存在相关性[13-16]，而另一些研究表明AFS可能有助于减肥[17]或对体重指数（BMI）没有影响[18]。鉴于五种FDA批准的AFS存在于数千种食品中[19]，这标志着一个明显而重大的知识差距。我们的初步数据表明，甜味敏感性降低了3倍，饮用两包Splenda增甜的饮料仅10天。这些数据提供了强有力的证据表明，反复暴露于三氯蔗糖降低了甜味强度的感知，最有可能是通过甜味受体的下调。总体而言，确定中央 味觉调节机制有关的增益调制和定向注意，以及一个可能的外围机制触发消费的AFS，拟议的工作将推进理解的来源，个人差异的口味是相关的食物选择和消费。

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.