School of Psychological Sciences, Monash Institute of Cognitive and Clinical Neurosciences (MICCN), Monash University, Melbourne, VIC, Australia.
Monash Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia.
Int J Obes (Lond). 2018 Mar;42(3):448-454. doi: 10.1038/ijo.2017.237. Epub 2017 Sep 25.
BACKGROUND/OBJECTIVES: Unhealthy dietary choices are a major contributor to harmful weight gain and obesity. This study interrogated the brain substrates of unhealthy versus healthy food choices in vivo, and evaluated the influence of hunger state and body mass index (BMI) on brain activation and connectivity.
SUBJECTS/METHODS: Thirty adults (BMI: 18-38 kg m) performed a food-choice task involving preference-based selection between beverage pairs consisting of high-calorie (unhealthy) or low-calorie (healthy) options, concurrent with functional magnetic resonance imaging (fMRI). Selected food stimuli were delivered to participants using an MRI-compatible gustometer. fMRI scans were performed both after 10-h fasting and when sated. Brain activation and hypothalamic functional connectivity were assessed when selecting between unhealthy-healthy beverage pairings, relative to unhealthy-unhealthy and healthy-healthy options. Results were considered significant at cluster-based family-wise error corrected P<0.05.
Selecting between unhealthy and healthy foods elicited significant activation in the hypothalamus, the medial and dorsolateral prefrontal cortices, the anterior insula and the posterior cingulate. Hunger was associated with higher activation within the ventromedial and dorsolateral prefrontal cortices, as well as lower connectivity between the hypothalamus and both the ventromedial prefrontal cortex and dorsal striatum. Critically, people with higher BMI showed lower activation of the hypothalamus-regardless of hunger state-and higher activation of the ventromedial prefrontal cortex when hungry.
People who are overweight and obese have weaker activation of brain regions involved in energy regulation and greater activation of reward valuation regions while making choices between unhealthy and healthy foods. These results provide evidence for a shift towards hedonic-based, and away from energy-based, food selection in obesity.
背景/目的：不健康的饮食选择是导致有害体重增加和肥胖的主要因素。本研究在体内研究了不健康与健康食物选择的大脑基质，并评估了饥饿状态和体重指数（BMI）对大脑激活和连接的影响。
受试者/方法：30 名成年人（BMI：18-38kg/m）进行了一项食物选择任务，涉及在由高热量（不健康）或低热量（健康）选择组成的饮料对之间进行基于偏好的选择，同时进行功能磁共振成像（fMRI）。使用与 MRI 兼容的味觉计向参与者提供选定的食物刺激。在禁食 10 小时后和饱腹时进行 fMRI 扫描。当选择不健康-健康饮料对与不健康-不健康和健康-健康选项相比时，评估大脑激活和下丘脑功能连接。结果以基于簇的家族性错误校正 P<0.05 为显著。
选择不健康和健康食物会引起下丘脑、内侧和背外侧前额叶皮层、前岛叶和后扣带的显著激活。饥饿与腹侧和背外侧前额叶皮层内的更高激活以及下丘脑与腹侧前额叶皮层和背侧纹状体之间的更低连接有关。至关重要的是，BMI 较高的人无论饥饿状态如何，下丘脑的激活都较低，而在饥饿时，腹侧前额叶皮层的激活更高。
超重和肥胖的人在进行不健康与健康食物之间的选择时，参与能量调节的大脑区域的激活较弱，而奖励评估区域的激活较高。这些结果为肥胖者在基于享乐主义而非基于能量的食物选择方面的转变提供了证据。
