Age Differences In Brain Networks During Task Preparatio

Task preparation allows us to respond flexibly and quickly to environmental events and plan ahead for actions specific to environmental conditions.In the laboratory,researchers use the task prompt paradigm to study the psychological mechanisms of the task preparation process.In such a paradigm,subjects are usually required to switch between two tasks.Task switching results in increased reaction time and decreased accuracy,which is called switching cost.Task preparation will reduce the conversion cost in the process of task conversion.Research has found that knowing which task to perform in advance leads to a reduction in reaction time.In addition,older adults do not prepare for task-switching as effectively as younger adults,especially when they show impaired task-switching ability when time for task preparation is reduced.So far,studies have only identified which brain regions are involved in task preparation,and although their role in task preparation has been described,how these brain regions communicate has been unclear until now,especially lacking evidence of functional connections.The patterns of connections within and between large-scale brain networks provide a unique perspective for many studies and add a lot of research results,which has become an important index in the field of cognitive neuroscience.Therefore,exploring the network basis of task preparation is essential to make up for the shortcomings of existing theories and improve our understanding of task preparation.Therefore,by directly measuring the changes of functional connectivity in task state,this study explores the interactions between brain regions during task preparation period from the perspective of large-scale brain networks.Based on the above analysis,this study will start from the background of large-scale brain networks to explore the neural mechanism of task preparation in young and old people.Using a taskswitching paradigm often used in task preparation,we designed event-related f MRI experiments with behavioral and brain data collected from young and old adults.The analysis in this study included activation analysis,ROI analysis,generalized psychophysiological interaction(g PPI)analysis,and correlation analysis between functional connection and behavioral performance.The purpose of activation analysis was to identify the activated brain regions of the two groups of subjects during task preparation.In this study,135 brain regions from the six brain networks in the Power 264 template were used as seed points for functional connectivity analysis(effective connectivity),so as to measure the changes in functional connectivity between brain regions under the condition of preparation versus unpreparation.Correlation analysis was used to explore the relationship between these functional connections and readiness effects.Behavioral results showed that young and old people had significantly lower switching costs in the prepared condition than in the unprepared condition.In addition,the readiness effect of young people was significantly smaller than that of older people.Simple effect analysis showed that there was no significant difference between young people and old people in preparation condition,but significant difference in unpreparation condition.This suggests that,with adequate preparation,the behavior of older people can approach that of younger people.In activation analysis,a large number of brain regions distributed in the frontoparietal region were found to be activated,including bilateral AI,bilateral ACC,d ACC,bilateral DLPFC,bilateral IPL,bilateral IPS,bilateral SPL,PCC,left IFJ and temporal lobe region.These regions were distributed in six brain networks: CON,DMN,FPN,SN,DAN and VAN.ROI results showed that young people’s readiness was positively correlated with activation levels of left IPL and left dl PFC.IPL is associated with stimulus-response(S-R)mapping,and dl PFC plays a key role in the task target activation or task update phase.Readiness in older adults was positively correlated with activation levels in the left precuneus,which may be a compensatory overactivation.The results of intra-network connection strength analysis showed that,compared with the elderly,the internal connectivity of DMN,SN and DAN was greater in young people during task preparation.The connectivity between DMN and CON/FPN/SN/DAN was higher,and the connection strength between CON and DAN was stronger.Correlation analysis showed that the connection matrix values of DMN and the other five brain networks were positively correlated with the readiness effect in the elderly,but not in the young.This suggests that there is a difference in the distribution pattern of DMN-centered connections between young and old adults during task readiness,and that this difference may explain task readiness performance between the two age groups.Specifically,DMN is related to memory,and better behavior in older adults may be achieved by compensating for memory networks.