The Default Mode Network Research Related To Normal Food Intake With Resting State Functional Magnetic Resonance Imaging

ObjectiveAlthough most previous studies focused on the functional brain imaging applying gastrointestinal invasive stimuli during task status,for example,balloon distension,little attention has been paid on the default mode network(DMN)at rest-ing state especially during normal food intake in healthy subjects.This study intend to collect imaging datas under four different time points during normal food intake and observe functional connectivity(FC)variations applying resting fMRI,further explore the influence of normal food intake on the DMN.MethodsFifteen healthy and eligible participants(8 males and 7 females)have superv-ised consumptions of a standard experiment diet(250 mL lactose free milk,four pieces of toast and an egg).In our study,we collected resting state blood and oxygen level dependence(BOLD)signals under four different gastrointestinal physiological states:fasting state(Fs~7:30 a.m),postprandial immediately(Pi~8:00 a.m),2h postp-randial(P2~10:00a.m),before lunch(Bf~12:00 a.m)during normal food intake.All participants were required to monitor blood glucose by a simple needle test and complete subjective ratings of hunger and fullness per scanning.Then we extracted the DMN using independent component analysis(ICA)and FC strength variation of four group imaging datas were analysed by repeated measure ANOVA using an in-house programme to receive significant different brain areas.FC z-values in signifi-cant different brain areas were extracted and analysed for inter-group multiple comparisons using LSD-t test in repeated measures by the means of statistical pack-age for social science(SPSS).Correlation analyses between blood glucose,hunger rating score and connectivity strength in the significant different brain areas were respectively performed.Blood glucose and hunger rating scores were entered as independent variable to correlate with connectivity strength.ResultsWe observed that significant difference of FC mainly located in the anterior cingulate cortex(ACC)and medial orbital frontal cortex(mOFC)under four different gastrointestinal physiological states.Compared with the Fs state,FC in the ACC and mOFC was reduced in the Pi state and the P2 state.Compared with the Pi state and the P2 state,FC in the ACC and mOFC was enhanced in the Bf state.Additional-ly,connectivity strength in the ACC and mOFC was negatively correlated with bloo-d glucose level,whereas positively correlated with hunger rating score.ConclusionFC variations in the ACC and mOFC of the DMN under four different gastrointestinal physiological states suggest that the DMN generates certain alterations during normal food intake and the variation of connectivity strength may act as the fluctuation of blood glucose and subjective hunger sensation.Our hypothesis of “potential foraging state”in the DMN at the resting state is probably the potential brain response specific to food intake behavior.