The Neurocognitive Mechanisms Of Food-related Intentional Inhibition In Individuals With Overweight

Overweight has become the greatest threat to public health in the 21 st century,and the World Health Organization estimates that the proportion of overweight and obese adults is as high as 40%worldwide(WHO.,2021).Currently,the number of overweight people in China is increasing rapidly and has already been the highest in the world(Wang et al.,2019).Overweight is characterized by excessive accumulation of adipose tissue and is often accompanied by other health problems such as diabetes,hypertension,coronary heart disease,and cerebrovascular disease(Hruby & Hu,2015).In addition,being overweight increases the incidence of mental health problems such as anxiety and addictive behaviors,and negatively affects brain development and cognitive abilities(Stice &Yokum,2021).According to the inhibitory control deficit theory of overweight/obesity,overweight individuals have poor inhibitory control over food cues(Lowe et al.,2019;Meng et al.,2020),which is particularly evident in high-calorie food cues(Liu,Gao et al.,2020).Inhibitory control reperesents the ability to withhold individuals’ dominant responses(Gerdan & Kurt,2020)and can be divided into two components depending on the degree of involvement of the individual’s subjective consciousness(Filevich et al.,2012;Weidacker et al,2021): inhibitory behaviors triggered by external instructions(reactive inhibition)and those voluntarily endogenous to the individual(intentional inhibition).Previous research on inhibitory control in overweight individuals has focused on reactive inhibition(Gerdan & Kurt,2020;Liu,Gao,et al.,2020),and few studies have examined inhibitory control in overweight individuals from the perspective of intentional inhibition.Previous studies have shown that the neural mechanisms of intentional inhibition differ from reactive inhibition(Lynn et al.,2014;Parkinson & Haggard,2015;Si et al.,2021).And intentional inhibition is involved in the control of impulsive behaviors such as drinking and gambling(Liu,van den Wildenberg,et al.,2020;Lynn et al.,2014),which are similar to the preference for food stimuli in overweight/obese individuals(Lowe et al.,2019).Therefore,in order to gain a more comprehensive understanding of inhibitory control in overweight individuals,the present study examined the food-related intentional inhibition in overweight individuals from a new perspective of intentional inhibition.Specifically,with a total of eight experiments in three studies,this paper examines the cognitive and neural performances of food-related intentional inhibition in overweight individuals using the modified food-related go/no-go/choose task,reveals the underlying neural mechanisms combining EEG and MRI techniques,and explores the predictive effects of neural indicators related to intentional inhibition on future body compositions.Study 1 examined the performance of food-related intentional inhibition in overweight individuals in different experimental contexts in three experiments.Experiment 1 used a modified food-related go/no-go/choose task and found that the RT of intentional trials was greater than that of reactive trials,suggesting that this modified task was able to distinguish intentional inhibition from reactive inhibition.However,no differences of intentional inhibition performance were observed between overweight and normal weight individuals.Experiment 2 combined the preparation period paradigm and the food-related go/no-go/choose task to examine the performance of food-related intentional inhibition in high,medium,and low response preparation conditions in overweight individuals.Results revealed that the proportion of intentional response was significantly greater in overweight than that in normal weight individuals.Moreover,only in overweight individuals,there was no difference in the RT of high-calorie food cues between the medium and the high level of response preparation.These results indicate that overweight individuals have reduced intentional inhibition and the elevated response readiness to high-calorie foods is completed in a shorter period of time,i.e.the level of response readiness barely increases with increasing readiness time after >300ms.Experiment 3 combined a subliminal priming paradigm with the food-related go/no-go/choose task to examine the performance of intentional inhibition in overweight individuals after positive-or negative-compatibility latencies.Results showed that positive-compatibility latencies increased the proportion of intentional responses to high-calorie food stimuli in overweight individuals,and to low-calorie food stimuli in normal-weight individuals;negative-compatibility latencies reduced the RT of intentional responses only in overweight individuals.These results suggest that overweight individuals are more susceptible to unconscious information and thus less able to voluntarily withhold their response to food cues.Study 1 provided behavioral evidence for reduced food-related intentional inhibition in overweight individuals.Study 2 explored electrophysiological activities,brain gray matter volume changes,and spontaneous neural activities associated with food-related intention inhibition in overweight individuals in three experiments.Experiment 4 used the food-related go/no-go/choose task combined with EEG recordings and found that overweight individuals evoked greater N2 a and P2 amplitudes.These results suggest that overweight individuals need to allocate more early attentional resources(P2)during intentional inhibition of food stimuli and are less able to recruit cognitive resources to complete pre-motor inhibition(N2a).Experiment 5 examined between-group differences in brain gray matter volume(GMV)and structural covariance connectivities.Results showed that poorer performance of food-related intentional inhibition in overweight individuals was associated with reduced GMV in the medial frontal cortex.The strength of covariant connections between the medial frontal cortex and the cerebellum,temporal cortex,and orbitofrontal cortex increased,while the strength of covariant connections with the insula and striatum decreased.This indicates that the structural covariance relationships between brain regions associated with intentional inhibition and diet-and reward-related regions are altered in overweight individuals.Experiment 6,based on resting-state functional magnetic resonance imaging data,revealed that the strength of resting-state functional connections(rs-FC)between the medial frontal cortex and the cerebellum,middle temporal gyrus,posterior cingulate gyrus,and postcentral gyrus increased in overweight individuals,whereas the strength of functional connections with the insula and the nucleus accumbens diminished,and that these rs-FCs were correlated with the performance of food-related intentional inhibition.These findings suggest that activities in brain regions associated with intentional inhibition in overweight individuals is difficult to neuromodulate the activities in brain regions associated with eating and reward.Study 2 provides neural evidence for reduced food-related intentional inhibition in overweight individuals.Study 3 examined the structural covariant connectivities/resting-state functional connectivities in brain regions involved in food-related intentional inhibition and further explored the predictive role of these connectivity patterns on future body compositions through restrained eating in two experiments.Experiment 7 examined the predictive role of food-related intentional inhibition associated structural covariant connectivities on body compositions after 1 year.These results showed that the covariant connection strength between the medial frontal cortex and the cerebellum increased in overweight individuals,and that this connectivity pattern predicted changes of fat mass index(FMI)and waist-to-height ratio(WHt R)after 1 year through restrained eating.Experiment 8examined the predictive effect of rs-FCs associated with food-related intentional inhibition on body compositions after 1 year.The results showed that overweight individuals had increased rs-FCs between brain regions associated with intentional inhibition and the postcentral gyrus and decreased rs-FCs with the middle temporal gyrus and precuneus.Moreover,these connectivity patterns predicted body mass index(BMI),waist height ratio and FMI,and FMI change after 1 year through restrained eating.Study 3 demonstrates that the neural performances of food-related intentional inhibition predict individuals’ future body compositions,which provides more stable evidence for the relationship between overweight and food-related intentional inhibition.Taken together,these results suggest that the ability of food-related intentional inhibition is decreased in overweight individuals.Larger P2 and N2 a amplitudes may be electrophysiological markers,and structural covariance connectivity/resting-state functional connectivity patterns between brain regions associated with intentional inhibition and regions associated with eating and reward may be neural imaging mechanisms of the decreased ability of intentional inhibition in overweight individuals.And these neural indicators may predict individuals’ future body compositions.The main innovations of this study include: first,theoretical innovation.From a new perspective of intentional inhibition,it was found for the first time that overweight individuals had reduced intentional inhibition of food cues,and overweight individuals performed worse in intentional inhibition than reactive inhibition.The electrophysiological basis for this is the enhanced activity of the early ERP component(N2a,P2).It was of particular importance that the electrophysiological marker of intentional inhibition was refined from N2 to N2 a.The imaging basis of this is the decreased spontaneous neural activity and reduced gray matter volume in brain regions associated with intentional inhibition(e.g.,medial frontal cortex),and altered patterns of its connectivity to diet-(e.g.,cerebellum)and reward-related regions(e.g.,insula).And a model of dynamic intentional inhibition of food cues in overweight individuals was constructed based on the above findings.Second,methodological innovation.Adapting the food-related go/no-go/choose task,the intentional inhibition measurement paradigm is firstly applied to the study on behavioral and neural mechanisms in overweight individuals;combining ERP and MRI techniques to explore the temporal and spatial characteristics of the cognitive process of food-related intentional inhibition in overweight individuals;combining cross-sectional studies and follow-up tasks to explore the persistent effects of intentional inhibition in the dynamic changes of overweight.Third,application value.Based on the new findings of the present study on the performance of food-related intentional inhibition in overweight individuals,it provides a cognitive solution for guiding overweight individuals to improve their eating behavior and weight management in the future,as well as a neural target for conducting neural interventions.