1 Laureate Institute for Brain Research, Tulsa, USA.
2 Center for Health Behavior Neuroscience, University of Kansas Medical Center, Kansas City, USA.
J Psychopharmacol. 2017 Nov;31(11):1475-1484. doi: 10.1177/0269881117728429. Epub 2017 Sep 25.
Obesity is fundamentally a disorder of energy balance. In obese individuals, more energy is consumed than is expended, leading to excessive weight gain through the accumulation of adipose tissue. Complications arising from obesity, including cardiovascular disease, elevated peripheral inflammation, and the development of Type II diabetes, make obesity one of the leading preventable causes of morbidity and mortality. Thus, it is of paramount importance to both individual and public health that we understand the neural circuitry underlying the behavioral regulation of energy balance. To this end, we sought to examine obesity-related differences in the resting state functional connectivity of the dorsal mid-insula, a region of gustatory and interoceptive cortex associated with homeostatically sensitive responses to food stimuli. Within the present study, obese and healthy weight individuals completed resting fMRI scans during varying interoceptive states, both while fasting and after a standardized meal. We examined group differences in the pre- versus post-meal functional connectivity of the mid-insula, and how those differences were related to differences in self-reported hunger ratings and ratings of meal pleasantness. Obese and healthy weight individuals exhibited opposing patterns of eating-related functional connectivity between the dorsal mid-insula and multiple brain regions involved in reward, valuation, and satiety, including the medial orbitofrontal cortex, the dorsal striatum, and the ventral striatum. In particular, healthy weight participants exhibited a significant positive relationship between changes in hunger and changes in medial orbitofrontal functional connectivity, while obese participants exhibited a complementary negative relationship between hunger and ventral striatum connectivity to the mid-insula. These obesity-related alterations in dorsal mid-insula functional connectivity patterns may signify a fundamental difference in the experience of food motivation in obese individuals, wherein approach behavior toward food is guided more by reward-seeking than by homeostatically relevant interoceptive information from the body.
肥胖从根本上说是一种能量平衡紊乱。在肥胖个体中，消耗的能量多于消耗的能量，导致脂肪组织过度积累而导致体重增加。肥胖引起的并发症，包括心血管疾病、外周炎症升高和 II 型糖尿病的发展，使肥胖成为发病率和死亡率的主要可预防原因之一。因此，了解能量平衡行为调节的神经回路对个人和公共健康都至关重要。为此，我们试图检查与肥胖相关的背侧中脑岛静息状态功能连接的差异，该区域与对食物刺激的稳态敏感反应有关。在本研究中，肥胖和健康体重个体在不同的内感受状态下完成了静息 fMRI 扫描，既在禁食时又在标准餐后进行。我们检查了中脑岛在餐前与餐后功能连接的组间差异，以及这些差异与自我报告的饥饿感评分和餐食愉悦感评分的差异有何关系。肥胖和健康体重个体的背侧中脑岛与多个参与奖励、评估和饱腹感的大脑区域之间存在相反的进食相关功能连接模式，包括内侧眶额皮质、背侧纹状体和腹侧纹状体。特别是，健康体重参与者的饥饿感变化与内侧眶额皮质功能连接的变化之间存在显著的正相关关系，而肥胖参与者的饥饿感与中脑岛的腹侧纹状体连接之间则存在互补的负相关关系。这些与肥胖相关的背侧中脑岛功能连接模式的改变可能表明肥胖个体在食物动机体验方面存在根本差异，其中对食物的接近行为更多地受到奖励寻求的指导，而不是来自身体的与稳态相关的内感受信息。
