Zhang Bin, Tian Derun, Yu Chunshui, Zhang Jing, Tian Xiao, von Deneen Karen M, Zang Yufeng, Walter Martin, Liu Yijun
Department of Anatomy, Tianjin Medical University, Tianjin, China; Clinical Affective Neuroimaging Laboratory, Department of Psychiatry, Otto von Guericke University, Magdeburg, Germany.
Department of Anatomy, Tianjin Medical University, Tianjin, China.
Neurosci Lett. 2015 Jan 1;584:156-61. doi: 10.1016/j.neulet.2014.10.020. Epub 2014 Oct 20.
Obesity as a chronic disease has become a global epidemic. However, why obese individuals eat more still remains unclear. Recent functional neuroimaging studies have found abnormal brain activations in obese people. In the present study, we used resting state functional MRI to observe spontaneous blood-oxygen-level dependent (BOLD) signal fluctuations during both hunger and satiety states in 20 lean and 20 obese men. Using a regional homogeneity (ReHo) analysis method, we measured temporal homogeneity of the regional BOLD signals. We found that, before food intake, obese men had significantly increased synchronicity of activity in the left putamen relative to lean men. Decreased synchronicity of activity was found in the orbitofrontal cortex (OFC) and medial prefrontal cortex(MPFC) in the obese subjects. And, the ratings of hunger of the obese subjects were higher than those of the lean subjects before food intake. After food intake, we did not find the significant differences between the obese men and the lean men. In all participations, synchronicity of activity increased from the fasted to the satiated state in the OFC. The results indicated that OFC plays an important role in feeding behavior, and OFC signaling may be disordered in obesity. Obese men show less inhibitory control during fasting state. This study has provided strong evidence supporting the hypothesis that there is a hypo-functioning reward circuitry in obese individuals, in which the frontal cortex may fail to inhibit the striatum, and consequently lead to overeating and obesity.
肥胖作为一种慢性疾病已成为全球流行病。然而，肥胖个体为何进食更多仍不清楚。最近的功能神经影像学研究发现肥胖者大脑激活异常。在本研究中，我们使用静息态功能磁共振成像观察20名瘦男性和20名肥胖男性在饥饿和饱腹状态下的自发血氧水平依赖（BOLD）信号波动。使用局部一致性（ReHo）分析方法，我们测量了局部BOLD信号的时间一致性。我们发现，在进食前，肥胖男性相对于瘦男性，左侧壳核的活动同步性显著增加。肥胖受试者眶额皮质（OFC）和内侧前额叶皮质（MPFC）的活动同步性降低。而且，肥胖受试者在进食前的饥饿评分高于瘦受试者。进食后，我们未发现肥胖男性和瘦男性之间存在显著差异。在所有参与者中，OFC的活动同步性从禁食状态到饱腹状态增加。结果表明，OFC在进食行为中起重要作用，肥胖时OFC信号可能紊乱。肥胖男性在禁食状态下表现出较少的抑制控制。本研究提供了有力证据支持肥胖个体存在奖励回路功能低下的假说，即额叶皮质可能无法抑制纹状体，从而导致暴饮暴食和肥胖。
