Neuroeconomics of sugars: Glucose vs. fructose effects on reward signaling

新陈代谢状态会影响行为，在很大程度上是为了维护体内平衡。然而，连接的路径 新陈代谢对决策的影响还不是很清楚。这项修订提案的核心思想是通过 结合内分泌学和神经经济学的见解和方法，我们可以更好地识别 将食物消费和行为联系起来的机制。在这里，我们特别关注比较它们的效果 两种糖(葡萄糖和果糖)对奖励信号和“延迟折扣”(价值倾向)的影响 作为其延迟的函数，奖励较少)。葡萄糖和果糖的影响截然不同。 内分泌功能(包括葡萄糖后循环胰岛素和GLP-1的增加)与中枢神经系统 活动(包括葡萄糖后VTA和黑质内多巴胺释放的更大衰减)。 有理由相信，这些识别的差异可能会导致延迟贴现的差异。 具体地说，我们假设，与更大但更延迟的奖励相比，更倾向于立即奖励的倾向 在摄入果糖后将比摄入葡萄糖后更大。考虑到直接决策与肥胖和问题药物使用等负面健康后果之间的联系，这将是 对健康有重大影响。受试者(N=36)将完成三种功能磁共振 成像(FMRI)会议，每次在隔夜禁食后消费以下任一种：水，75克果糖 饮料，或75克葡萄糖饮料。在扫描仪之外，参与者将完成一项使用凸预算的任务 估计效用函数和贴现函数。在功能磁共振成像期间，参与者将完成：1)修改后的“货币 激励任务“，具有即时和延迟奖励，以及2)”延迟折扣任务“，其中 参与者在即期和延迟付款之间做出选择。在后者中，选项将是个性化的 困难(考虑到参与者的折扣和折扣，即时和延迟选项同样具有吸引力 实用程序)。神经成像分析将重点放在已建立的奖励通路和额顶网络上 在决策任务中被招募。通过附加到正在进行的单独研究，该研究包括 测量对相同糖的内分泌反应，我们还将能够调查是否存在差异 在初步研究中，测量指标与内分泌的个体差异有关(可能受其影响) 对葡萄糖和果糖的反应。

Metabolic state affects behavior, in large part to defend homeostasis. However, the pathways linking metabolism to decision-making are not well understood. The core idea of this revised proposal is that by combining insights and methods from endocrinology and neuroeconomics, we can better identify mechanisms linking food consumption and behavior. Here we focus specifically on comparing the effects of two sugars (glucose and fructose) on reward signaling and “delay discounting” (the tendency to value rewards less as a function of their delay). Glucose and fructose have dramatically different effects on endocrine function (including greater circulating insulin and GLP-1 after glucose) and central nervous system activity (including greater attenuation of dopamine release within the VTA and substantia nigra after glucose). There is reason to believe that these identified differences may lead to differences in delay discounting. Specifically, we hypothesize that the tendency to prefer immediate reward over larger but more delayed reward will be greater after fructose consumption than after glucose consumption. Given links between immediate-oriented decision making and negative health consequences like obesity and problem drug use, this would have significant health implications. Participants (N = 36) will complete three functional Magnetic Resonance Imaging (fMRI) sessions, each after overnight fast followed by consumption of either: water, a 75g fructose drink, or a 75g glucose drink. Outside the scanner participants will complete a task that uses convex budgets to estimate utility and discount functions. During fMRI, participants will complete: 1) a modified “Monetary Incentive Task” with immediate and delayed rewards, and 2) a “Delay-Discounting Task” in which the participant makes choices between immediate and delayed money. In the latter, options will be individualized to be difficult (the immediate and delayed options similarly attractive given the participant’s discounting and utility). Neuroimaging analyses will focus on established reward pathways and on fronto-parietal networks recruited during the decision making task. By attaching to an ongoing separate study that includes measurement of endocrine responses to the same sugars, we will also be able to investigate whether variance in the primary study measures is associated with (and possibly mediated by) individual differences in endocrine response to glucose and fructose.