Biobehavioral Mechanisms Underlying Non-homeostatic Eating

考虑到在我们的环境中非常美味的食物的普及和可获得性，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记得，当我们刚刚吃饱了的时候，还是选择了甜点，或者当我们在准备考试的时候吃了一袋薯条。对饥饿以外的暗示做出反应的进食被广泛称为“非稳态进食”，这种行为被认为与加拿大和世界大部分地区肥胖症的增加有关。对非稳态进食的研究主要集中在解释谁最有可能参与这些饮食模式的个体差异；然而，很少有人解决与这种行为何时、为什么以及如何发生相关的具体问题。尽管有令人信服的理论表明奖赏和控制相关的神经回路在驱动非稳态进食中所起的作用，但在人类身上测试这些模型的直接证据有限。特别是，许多评估享乐饮食(即，为快乐而吃)的研究衡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稳态进食和非稳态进食的机制的能力。因此，这项研究计划的首要目标是更好地描述导致人类非稳态进食的神经生物学机制。这些目标将通过一系列研究来实现，这些研究涉及几个不同但相关的研究问题。项目1将评估非稳态进食的结构、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(即背外侧前额叶皮质)在调节进食动机和在没有饥饿的情况下进食方面的作用。我们所有的研究将包括男性和女性，以增加研究结果的概括性，并对潜在的性别和非稳态饮食的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.