The Influence Of Self-control On Individual Food Reward Decision Making And Its Neural Mechanism

Food is a natural rewarding stimulus,which promotes human to seek for it because of its instinctive desire and need for reward.There are three important theoretical models at this moment about the role of food reward in the cause of obesity,namely,the incentive sensitization theory of addiction/obesity,the reward-surfeit theory of obesity,and the reward deficit theory of obesity.All of three theoretical models are highly acceptable in the explanation of the neural mechanisms offood reward.In the meantime,all of the three theoretical models illustrate the neural mechanism of food reward decision-making from the perspective of reward(impulse)system in the striatum,which the role of the prefrontal control system in food reward system were unanimously ignored.It can be seen from the dual-system theory model that the reward-impulse system and the prefrontal-control system play an antagonistic role in the control of the individual eating behavior.Self-control is that the individual consciously resists the temptation to meet immediate needs,and regulates the impulsive behavior,which aims to pursuit of long-term goals that can bring greater overall goals.Everyday,individuals make dozens of choices between an alternative with higher overall and a more tempting but ultimately inferior option.Optimal decision-making requires self-control.In that way,the self-control of the food reward decision-making is that individuals make decisions in food reward choices consciously to control their impulsion for the short-term benefits that can meet the needs of direct taste,in order to obtain the overall benefit,namely the health.This behavior reflects the individuals'choice of food reward,which means that they are willing to give up the immediate interests of the foundation for more valuable long-term results.Nevertheless,how does self-control affect food reward decision-making?And what is the underlying neural basis and operating mechanisms of self-control?Therefore forth-three female university volunteers were chosen through the campus ads for this study,and all are healthy and right-hand without metabolic diseases and taking psychiatric drugs.This study combined behavioral experiments with fMRI(functional magnetic resonance imaging,fMRI)approach,from perspective of self-control,to study the decision-making of food reward.In this study,there were two rating tasks including the taste rating and the health rating of food reward,while the 2AFC(two alternative forced choice)task was used in the decision phase.This study focused on the following two questions:1)to investigate the relationship between self-control and food reward decision-making;2)to explore the neural mechanisms underlying the self-control affecting food reward decision-making.This study contained two experiments,and the first was the behavioral experiment,which contained the taste and health rating tasks about the food reward and the measurement of DEBQ(Dutch Eating Behavior Questionnaire).The DEBQ was used to evaluate the personality traits of volunteers.It was expected that the scores of DEBQ were significantly correlated with taste and health rating of food reward,respectively.The behavioral results were 1)The taste rating score of high calorie food pictures was significant lower than that of the low one;2)The taste rating of food images of participants was only significantly related to their DEBQ's scores.More concretely,the DEBQ-EM(emotional eating)score of the participants had significant negative correlation with the taste rating of the low calorie food(r=-.323~*,p<.05),and the DEBQ-EX(external eating)score of the participants had significant positive correlation with the health rating of the high calorie food(r=.346~*,p<.05).The first behavioral study had found the taste and health property differences of food reward.And The second combined the behavior measure with f MRI(functional magnetic resonance imaging)techniques to explore the underlying neural mechanism of self-control which affected the food reward decision.Unexpectedly,the behavioral results were that the DEBQ scores were not significantly correlated with food reward decision-making.The fMRI findings indicated that:1)Comparing the hemodynamic responses of the self-control in success vs.failture,we observed activation in the dorsolateral prefrontal cortex(DLPFC),while the activation in the middle cingulate(MCC)in failture vs.success;2)Activation in the putamen and MCC strongly correlated with the degree of dietary restraint(the score of DEBQ-R)respectively under the not-do and do conditions.Cortical activation in the DLPFC was known to underpin top-down control,and in the MCC represented the focus of attention.Conclusions:it was that both the DLPFC and the MCC played an important role in self-control of food reward decision-making,and the two mechanisms of self-control underlying the do and not-do conditions were different.