Biobehavioral Mechanisms Underlying Non-homeostatic Eating

考虑到在我们的环境中，美味食物的普遍存在和可获得性，人类经常在没有任何生理需要的情况下进食。事实上，我们中的大多数人都能回忆起我们在刚吃完一顿饭之后仍然选择甜点的经历，或者我们在准备考试的时候吃了一袋薯条的经历。根据饥饿感以外的线索进食被广泛地称为“非稳态进食”，这种行为与加拿大和世界大部分地区肥胖人数的上升有关。非体内平衡饮食的研究集中在个体差异上，以解释谁最有可能参与这些饮食模式；然而，很少有人提出与这种行为发生的时间、原因和方式有关的具体问题。尽管关于奖励和控制相关的神经回路在驱动非稳态饮食中的作用的理论令人信服，但在人类身上测试这些模型的直接证据有限。特别是，许多评估享乐性饮食（即，为了快乐而吃）的研究测量了短期食物限制后的食物摄入量。这种方法限制了我们完全区分调节体内平衡与非体内平衡饮食机制的能力。因此，本研究项目的首要目标是更好地描述导致人类非体内平衡饮食的神经生物学机制。这些目标将通过解决几个不同但相关的研究问题的一系列研究来实现。项目1将评估非稳态饮食的结构有效性和多维方面及其生物行为相关性。项目2将直接评估特定大脑区域（即背外侧前额叶皮层）在调节进食动机和在没有饥饿的情况下进食的作用。我们所有的研究都将包括男性和女性，以增加研究结果的普遍性，并对非体内平衡饮食的潜在性别和性别差异进行探索性分析。

Given the prevalence and accessibility of highly palatable foods in our environment, humans often eat in the absence of any physiological need for food. Indeed, the majority of us can recall times when we opted for dessert despite being full from the meal we just consumed, or times when we ate a bag of chips while studying for an exam. Eating in response to cues other than hunger is broadly referred to as “non-homeostatic eating,” and this behaviour has been implicated in the rise of obesity across Canada and much of the world. Studies of non-homeostatic eating have focused on individual differences that explain who is most likely to engage in these eating patterns; however, few have addressed specific questions related to when, why, and how this behaviour occurs. Despite compelling theories for the role of reward- and control-related neural circuitry in driving non-homeostatic eating, there is limited direct evidence testing these models in humans. In particular, much research assessing hedonic eating (i.e., eating for pleasure) measures food intake after short-periods of food restriction. This approach limits our ability to fully differentiate mechanisms that regulate homeostatic versus non-homeostatic eating. Thus, the overarching goals of this research program are to better characterize the neurobiological mechanisms that contribute to non-homeostatic eating in humans. These goals will be accomplished through a series of studies that address several distinct but related research questions. Project 1 will evaluate the construct validity and multidimensional aspects of non-homeostatic eating and their biobehavioural correlates. Project 2 will directly assess the role of specific brain regions (i.e., dorsolateral prefrontal cortex) in regulating motivation to eat and eating in the absence of hunger. All of our studies will include both men and women in order to increase the generalizability of findings and to conduct exploratory analyses of potential sex and gender differences in non-homeostatic eating.