Abstract
Obesity as a chronic disease is a major factor for insulin resistance and Type 2 diabetes, which has become a global health problem. In the present study, we used resting state functional MRI to investigate the amplitude of low frequency fluctuations of spontaneous signal during both hunger and satiety states in 20 lean and 20 obese males. We found that, before food intake, obese men had significantly greater baseline activity in the precuneus and lesser activity in dorsal anterior cingulate cortex (dACC) relative to lean subjects. Furthermore, after food intake, obese males had significantly lesser activity in dACC than lean males. We further found a significant positive correlation between precuneus activation and hunger ratings before food intake, while dACC activity was negatively correlated with plasma insulin levels before and after food intake. These results indicated that both precuneus and dACC may play an important role in eating behavior. While precuneus rather seemed to mediate subjective satiety, dACC levels rather reflected indirect measures of glucose utilization.
Highlights
Group effect P value reported altered function of the DMN in obesity individuals[10]
Instead of the functional connectivity, which focuses on the signal temporal synchronization of low frequency fluctuation (LFF) among different brain areas[12], amplitude of low frequency fluctuations (ALFF) takes the amplitude of brain activity as measured by BOLD signals in resting-state fMRI into account[13]
This effect was mainly driven by increases after feeding in controls while in obese individuals, ALFF was significantly increased in PCC (x = 9, y = − 33, z = 30, k = 1 74) after feeding
Summary
Group effect P value reported altered function of the DMN in obesity individuals[10]. The authors reported increased activation in ACC during the pre-meal condition and greater activation in medial prefrontal cortex in obese subjects in pre-meal and post-meal states. This altered activation in salience network was considered to be associated with the overeating through an imbalance between autonomic processing and award processing of food stimuli[9]. Two major factors (hunger and satiety state) mediating eating behavior were considered separately, disentangling subjective feeling of hunger from objective mechanisms of altered insulin concentration We expected that these two factors contribute differently in the context of satiety or hunger, while the primary regions of action were to be defined for the two mechanisms
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