The Neural Basis Of Inhibitory Control In Older Adults

Our country is gradually stepping into the aging society.The elderly population accounting for a growing proportion is driven by the birth rate decline and the rapid medical progress.All walks of life are paying more and more attention to the life quality of the elderly in their later years,aiming at maintaining the physical health,mental health and self-care ability of the elderly,hoping to achieve the goal of enjoying one’s old age in peace for every elderly person.The cognitive control function is very important for the elderly.Cognitive control refers to the psychological process of controlling one’s own behavior and thoughts to achieve a certain goal,of which the inhibitory control is one of the core components.It plays a key role in emotion regulation,memory retrieval,and decision making.The maintenance of inhibitory control function enables the elderly to have a good emotional state and maintain a healthy cognitive state.In the past two decades,with the wide application of neuroimaging technology,more and more researchers have explored the elderly’s related connectivity of large-scale neural network in resting-state data.Through this method,the functional integration and separation of the aging brain during inhibitory control can be explored more systematically.However,few studies have investigated the organizational changes of attentional-control-related neural network connectivity during aging based on large-scale neural networks in the inhibitory-control task.Therefore,based on the classic Stroop paradigm,this study investigated the changes in the connectivity between the six related neural networks in older adults with or without conflict.Specifically,two studies were conducted to explore the neural mechanism of inhibitory control in older adults by the morphology of neural networks and the regulatory effect of conflict conditions on it.In Study I,to investigate the changes of brain network connectivity during inhibitory control in the older adults with the modulation from experimental conditions,we used psychophysiological interaction analysis and modular interaction analysis to compare the functional connectivity(FC)between the younger and older groups,which is conducted under the consistent(with no conflict)and inconsistent(with conflict)conditions respectively.The results showed that:(1)Psychophysiological interaction analysis showed that the connectivity between default mode network(DMN)and frontoparietal network(FPN),Cingulo-opercular network(CON),ventral attention network(VAN)and dorsal attention network(DAN)increased with aging,showing a trend of brain networks dedifferentiation.The connectivity between DMN and CON,as well as the connectivity between DMN and FPN,was modulated by the experimental conditions,and the modulatory effects were different between the two age groups.(2)In the analysis of modular interaction,this study found that the network interaction between DMN and FPN and DMN and DAN in the elderly was greater than that in the young people under the non-conflict condition,while the network interaction within DMN showed the opposite result in the same condition with greater network interaction in younger participants.Differences between experimental conditions were further found between CON and DAN,DMN and SAN,FPN and SAN,FPN and DAN,within CON,and within FPN.However,in this study,we still observed a trend that the interaction between DMN and FPN,between DMN and DAN of younger adults was weaker than that of older adults under two experimental conditions.In short,the elderly showed a trend of dedifferentiation in the brain network during inhibitory control,showing the changes of between-network connectivity with DMN as the core.In addition,the network connectivity reorganized in response to the changes of conflict situations and the conflict situation regulation effect showed differences between the two age groups.In Study II,to investigate the changes of mutual influence between brain networks during inhibitory control in the older adults with the modulatory effects of experimental conditions,based on the results of Study one,a dynamic causal model was constructed under four conditions: 2(experimental condition: consistent condition,inconsistent condition)× 2(age group: younger group,older group)to explore the directed connectivity differences between the DMN and other attentional-control networks.Specifically,(1)we found that there were excitatory directed connections from DMN to CON,DMN to FPN,and DAN to DMN in the elderly under both experimental conditions,and the distribution of directed connections in the elderly under the incongruent condition could significantly predict their task accuracy under the corresponding condition.This result may be related to the neural compensation and the failure of DMN network inhibition during the task.(2)In younger adults,there was reciprocal excitatory directed connectivity only between DMN and VAN under both experimental conditions.The distribution pattern didn’t significantly predict the behavioral performance of young adults under both experimental conditions.In a word,the elderly and the younger adults show differences in the distribution pattern of directed connectivity in the process of inhibitory control,revealing distinction between brain working patterns of inhibitory control processes in the two age groups,which may explain the differences in behavior indicator between the two groups.In conclusion,on account of the results from Study I and Study II,this study summarized the dynamic changes of large-scale network in the older adults based on inhibitory control task.For the first time,we comprehensively investigated the changes of FC and effective connectivity distribution patterns of attentional-control-related brain networks in aging,as well as the changes of network connectivity distribution patterns in the presence or absence of cognitive conflict in the elderly.This study reconfirmed the neural dedifferentiation theory of aging,as the trend of network separation between attentional-control-related brain networks was observed to be weakened;The present study also provides another evidence for the neural compensation mechanism of inhibitory control in the older adults and validates the scaffolding theory of aging and cognition;Meanwhile,this study reveals the dynamic changes of the brain network mechanism in the older adults during the task and it’s been observed that the dynamic changes are modulated by the experimental conditions.