The Differences Of Chronotype-based In Executive Function After Sleep Deprivation

Sleep is very important for human health,lack of sleep often has a negative impact on people's health and cognition,which leads to problems in work and life.In experimental studies,the study of sleep loss uses the sleep deprivation(SD)paradigms to manipulate the duration or timing of sleep.The researchers believe that SD should particularly impair complex executive functions(EFs)that rely on the prefrontal regions,however,studies on this assumption have yielded inconsistent results.There is a general agreement that there are three core EFs: inhibition,working memory and cognitive flexibility,on which higher-order EFs are built.Researchers believe that the degree of cognitive impairment also depends on which cognitive domain/task is tested.Meantime,the researchers pointed out that individual differences in vulnerability to SD-associated cognitive impairments may be one of the factors that lead to inconsistent results.Some participants show minimal impairments in cognition(mainly sustained attention)under SD conditions and it is easier to use compensation mechanisms to cope with the adverse effects of SD,while some participants show marked cognitive impairments and it is difficult to use compensation mechanisms.In real life,circadian rhythmic expression differs among individuals and can be classified by chronotype(CT),which can be classified as morningness(MT,prefer to go to bed early and get up early)and eveningness(ET,prefer to go to bed late at night and get up late).However,existing research pay less attention to whether and how the EFs after SD are affected by the individual differences in chronotype and the underlying neural basis.Therefore,in study 1,a questionnaire survey was conducted to investigate whether there is a moderating effect of chronotype in the relationship between sleep and executive functions.In study 2,functional magnetic resonance imaging(f MRI)were used to explore whether and how the core components of EFs(inhibition,experiment 2;working memory,experiment 3;cognitive flexibility,experiment 4)after SD are affected by chronotype and the underlying cognitive neural mechanisms.In study 3,diffusion tensor imaging(DTI)and resting-state f MRI(rs-f MRI)were combined to explore the brain structure basis(experiment 5)and functional basis(experiment 6)behind the mechanisms how does chronotype affect EFs after SD.In study 1,a questionnaire survey was conducted to test whether there is a moderating effect of chronotype in the relationship between the sleep and executive functions.The results showed that the poor sleep quality is associated with impaired execution function;the eveningness is associated with poorer sleep quality;the eveningness is associated with impaired execution function;chronotype moderate positively the relationship between sleep quality and execution function.The relationship between sleep quality and EF is stronger in people with higher scores of chronotype(morningness)than in people with lower scores of chronotype(eveningness).We speculate that sleep quality significantly affects the executive function,and ET individuals need to work in the morning,which is inconsistent with their preferred time of activities.The social jetlag occurs chronically and is more prominent in ET individuals,may directly lead to changes in sleep quality and patterns,thereby impairing EF.In addition,the relationship between sleep quality and EF in ET individuals may be affected by personality,emotion,social jetlag,and unhealthy lifestyle and other factors.This may be part of the reason why sleep quality is more strongly associated with EF in MT individuals than in ET individuals.In experiment 2,using f MRI,the present study attempted to explore whether and how the neurobehavioral function of response inhibition after SD was affected by chronotype,24 MT individuals and 21 ET individuals were conducted the Go/No-Go task in the session of rested-wakefulness(RW)and SD.(1)Behaviorally,compared with the RW,SD led to an increase in RT of Go trials,more attentional lapses,increased sleepiness,and worse mood indices.Regardless of SD or not,ET individuals demonstrated a lower accuracy of No-Go trials,as well as higher subjective ratings of sleepiness,exhausted mood and task difficulty than MT individuals.(2)On the neural level,there is a significant chronotype × session interaction effect in the inhibition-related IFG region.SD resulted in decreased inhibition-related IFG activation in MT individuals and in increased IFG activation in ET individuals.(3)Brain-behavior correlation analysis showed that the IFG activation in ET individualsafter SD was positively correlated to the subjective ratings of sleepiness and effort put into the task.We believed that ET individuals demonstrated an increased IFG activation after SD,which can be interpreted as a compensatory response to the adverse effects of SD.In experiment 3,using f MRI,the present study attempted to investigate whether and how the neurobehavioral function of working memory after SD was affected by chronotype,24 MT individuals and 20 ET individuals were conducted the N-back task in the RW and SD session.The N-back task was used with three levels(1-back,1B;2-back,2B;3-back,3B)of difficulty(task load),so this study also explored whether the performance of working memory after SD was affected by task difficulty.(1)Behaviorally,compared with the RW,SD led to a lower RT of N-back task(N = 1,2,3),more attentional lapses,increased sleepiness,worse mood indices,higher task difficulty and more difficult to concentrate.Regardless of sleep deprivation or not,ET individuals demonstrated more attentional lapses,increased sleepiness and more exhausted mood than MT individuals.More importantly,there is a significant chronotype × session interaction effect on the RT of 2-back task.SD resulted in a stable RT of 2-back task in MT individuals and in increased RT of 2-back task in ET individuals.(2)On the neural level,there is a significant chronotype × session interaction effect in the left inferior frontal gyrus(IFG)and middle temporal gyrus(MTG)brain areas related to task load(2B vs.1B,3B vs.1B).SD resulted in increased task-load related cerebral activation in MT individuals and in decreased cerebral activation in ET individuals.(3)Brain-behavior correlation analysis showed that,regardless of SD or not,the left IFG in MT individuals were positively correlated with the motivated and fresh moods and task motivation.In addition,the activation of left IFG in ET individuals after SD were positively correlated with better performance of N-back task.Accordingly,both chronotype and task difficulty affect the effect of SD on working memory.We speculate,regardless of SD or not,MT individuals demonstrated fewer attentional lapses,lower sleepiness and more fresh mood,making it easier for them to use the compensation mechanism to enhance the activation of frontal lobe at the adverse condition of difficult task and SD,thus maintain better task performance.On the contrary,regardless of SD or not,ET individuals demonstrated more attentional lapses,higher sleepiness and more exhausted mood,making it more difficult to use the compensation mechanism under the adverse conditions,and thus the performance was impaired.In experiment 4,using f MRI,the present study attempted to explore whether and how the neurobehavioral function of cognitive flexibility after SD was affected by chronotype,23 MT individuals and 16 ET individuals were conducted the cued task switching paradigm in the RW and SD session.(1)Behaviorally,compared with the RW,SD led to a longer RT of the task repeat trials,lower accuracy of task switch trials,more attentional lapses,higher sleepiness,worse mood and task indices.However,SD did neither impair the accuracy and RT of switch cost.Regardless of SD or not,ET individuals demonstrated more exhausted mood,longer RT of task repeat trials and lower accuracy of task switch trials than MT individuals.More importantly,there is a significant chronotype × session interaction effect on the accuracy of task switch trials.SD resulted in significantly reduced accuracy of task switch trials both in MT and ET individuals,but impaired performance in ET individuals was more severe.(2)On the neural level,there is a significant chronotype × session interaction effect in the anterior cingulate cortex(ACC)region during the period of task preparation(cue-target interval,CTI).SD resulted in a stable ACC activation in MT individuals and in decreased activation in ET individuals.(3)Brain-behavior correlation analysis showed that,after SD,the activation of ACC in MT individuals was positively related to the motivated mood and the activation of ACC in ET individuals was negatively related to the task difficulty.The ACC is prominent in the error detection and conflict monitoring.When the task switching occurs,the current task set conflicts with the previous task set,and task switching is easier to make mistake than task repetition,so the conflict monitoring and error detection is especially important in the preparation period of task switching.We speculated that,after SD,the better mood state of MT individuals may be the basis for them to maintain a stable activation of the ACC region,and thus demonstrated a relatively better task performance,while it was difficult for ET individuals to use the compensation mechanism in the face of difficult tasks to enhance cerebral activation to maintain the better performance.In experiment 5,using diffusion tensor imaging(DTI),the present study attempted to investigate the structural basis of individual differences in EF after SD were mediated by chronotype,26 MT individuals and 21 ET individuals underwent DTI scanning in the RW session.(1)The independent sample T tests were performed using complementary atlas-based tract-specific quantification analysis and voxel-based analysis(VBA)in the study.Consequently,both analyses yield similar results,fractional anisotropy(FA)value of MT individuals in the right cingulate gyrus washigher than that of ET individuals.(2)Brain-behavior correlation analysis showed that FA value of the cingulum in the MT individuals was positively correlated with the accuracy of No-Go trials in inhibition task at RW,and correlated with fresh-exhausted mood(negatively)and task motivation(positively)in working memory task at SD,in addition,it was positively correlated with positive mood state.However,FA value of the cingulum in the chronotypes was not correlated with the performance(RT and accuracy)of executive function after SD.We speculated that the structural integrity of the cingulum may be the structural basis of the individual difference in the executive function and mood regulation between chronotypes.In view of the complexity of higher-order EFs,it is necessary to further explore whether and how the structural basis of chronotypes to predict the performance of EF after SD using more elaborate study design and data analysis in the future.In experiment 6,using rs-f MRI,the present study attempted to explore the functional basis of individual differences in EF after SD were mediated by chronotype,26 MT individuals and 21 ET individuals underwent resting state scanning in the RW and SD session.In this study,ALFF(amplitude of low-frequency fluctuation),Reho(regional homogeneity),and RSFC(resting-state functional connectivity)analyses were used to test the interaction effects.(1)ALFF analysis showed that there were significant chronotype × session interaction effect in the posterior cingulate cortex(PCC)regions.SD resulted in stable ALFF in PCC in MT individuals and in decreased ALFF in PCC in ET individuals.(2)Reho analysis showed that there were significant chronotype × session interaction effect in the ventromedial prefrontal cortex(vm PFC),thalamus and superior frontal gyrus(SFG)regions.As for vm PFC region,SD resulted in stable Reho in MT individuals and in decreased Reho in ET individuals.As for thalamus and SFG region,SD resulted in stable or decreased Reho in MT individuals and in increased Reho in ET individuals.(3)RSFC analysis showed that there is a significant chronotype × session interaction effect in RSFC between PCC and insula.SD resulted in decreased RSFC between PCC and insula in MT individuals and in increased RSFC between PCC and insula in ET individuals.(4)Brain-behavior correlation analysis did not find the correlation between resting state neural activity in chronotypes and EF after SD.It shows that the spontaneous brain activity,regional homogeneity and functional connectivity at resting state after SD were influenced by chronotype.In MT individuals,the spontaneous neural activity and Reho of default mode network(DMN),in which PCC and vm PFC serve as the key hubs of DMN,Reho of thalamus,and functional adaptive decoupling between DMN(PCC)and anti-correlated networks(ACN,insula serve as a key hub of ACN)at resting state after SD are still robust.In ET individuals,SD resulted in reduced in the spontaneous neural activity and Reho of default mode network(DMN),in which PCC and vm PFC serve as the key hubs of DMN,and impaired functional adaptive decoupling between DMN and ACN.Meantime,ET individuals may compensate for the adverse effect after SD by increasing Reho in thalamus and sensorimotor gyrus(SFG).This may indicate an imbalance in activation-inhibition of neural activity at resting state in ET individuals after SD.We believe that,to a certain extent,the functional basis of the brain of chronotype at the resting state affects the performance of the EF after SD.In view of the complexity of higher-order EFs,it is necessary to further explore whether and how the functional basis of chronotypes to predict the performance of EF after SD using more elaborate study design and data analysis in the future.Overall,the study revealed that:(1)Chronotype moderate positively the relationship between sleep quality and EF.The relationship between sleep quality and EF is stronger in people with higher scores of chronotype(morningness)than in people with lower scores of chronotype(eveningness).(2)The neurobehavioral response of EF after SD is affected by chronotype,and the expression of individual differences will vary depending on the component or task of EF.(3)The DMN and the cingulum connecting to the DMN may be the main functional basis and structural basis for the neurobehavioral response of EF after SD mediated by chronotype.This study introduced chronotype into the study of EF after SD,expanded the research scope of individual differences in SD paradigm,and preliminarily investigated the issues of within-subjects and between-domain differences after SD.It is of great scientific value for exploring and improving the neurophysiological mechanism and gene mechanism of SD affecting EF.In addition,it is of great practical significance to comprehensively evaluate the causes of sleep disorders and cognitive impairment caused by sleep disorders and provide specific and personalized intervention.