Neuronal activity and its role in adiposity and food intake

利用正电子发射扫描和脑MRI，研究了饥饿和饱腹感的神经解剖学相关性。重要的是，对收集到的数据的分析表明，大脑中对奖励处理很重要的左背外侧前额叶皮层可能是一个饱腹感中心。无论是男性还是女性，进食后，肥胖者的左背外侧前额叶皮层的神经元激活程度都比瘦子低。此外，我们还证明，患有普瑞德-威利症的受试者实际上在同一区域失活。Prader-Willi患者由于无法抑制饱腹感而无法控制饥饿感，因此这种失活（相对于肥胖个体的激活程度较低）进一步证明了前额叶皮层在食欲控制方面的重要作用。

Using positron emission scanning and brain MRI, neuroanatomical correlates of hunger and satiety have been investigated. Importantly, analyses of this collected data has indicated that the left dorsolateral prefrontal cortex, an area of the brain important in reward processing, may be a satiety center. Neuronal activation in the left dorsolateral prefrontal cortex following a meal is consistently lower in this area in obese versus lean individuals, in both men and women. Moreover, we demonstrated that in subjects with Prader-Willi there is actual deactivation of this same area. Prader-Willi patients have uncontrolled hunger due to failure of meals to suppress satiety, so this deactivation (as opposed to only lesser activation in obese individuals) is further evidence of an important role for the prefrontal cortex in appetite control. We then conducted a parallel design study of active anodal stimulation to the left dorsolateral prefrontal cortex versus sham in obese individuals. We again measured ad libitum energy intake, but also had a follow-up 4 week outpatient follow-up in which tDCS was continued three times per week. In addition to measuring ad libitum energy intake, we also measured hunger scores and conducted post meal snack food tests. In the parallel design study, we were not able to replicate the lower ad libitum energy intake or weight loss in the active treatment group, but we found a steady decrease in hunger and urge to eat scores and lower intake of snack foods after 4 weeks of treatment. These results indicate it may take weeks for the effect of tDCS to be manifest. We have begun a longer 9 week outpatient study which will include functional MRI of the brain prior to and following the first and final tDCS session to investigate the acute and chronic effects of tDCS on the pre-frontal cortex and other brain regions.