The Role Of The Fronto-parietal Network On Attentional Control:a TMS Study

Working memory(WM)is a memory system with limited capacity for temporary processing and storage of information.It provides the temporary storage space and information necessary for processing,such as reasoning,learning and language comprehension.However,the n-back task paradigm,as one of the classic cognitive experiments,has been used extensively for the study of WM related problems.In addition,the prefrontal cortex(PFC),as one of the most complex regions of the human cerebral cortex,has been the focus of research and controversy over the past few decades.Although the importance of PFC for high-level cognitive function is indisputable,it is not clear whether its specific functional function and whether there is functional division or how to divide.Therefore,this paper aims to explore the role of PFC in working memory by using Meta-analysis and repetitive transcranial magnetic stimulation(rTMS).In this paper,we first finished the Meta-analysis of the literature using the n-back paradigm and functional magnetic resonance imaging(fMRI)study of healthy subjects.We used the activation likelihood estimation(ALE)analysis method to analyze and explore the function of PFC and its sub-regions during WM.The results demonstrated consistent activation of a widespread fronto-parietal network from the main effect across analyses of different contrasts.Furthermore,we found that dorsolateral PFC(DLPFC)and rostral prefrontal cortex(rPFC),which two sub-regions of PFC,have a special role to working memory.Among them,DLPFC is more significant activated to memory load and age difference,and rPFC is engaged when problems involve multiple discrete cognitive processes.Furthermore,we used cTBS,which a popular stimulus mode of rTMS,to stimulate the rostrolateral PFC(RLPFC)and the rostromedial PFC(RMPFC),which the two sub-regions of rPFC,and explored the execution control function of rPFC in the working memory task with task switching.The experimental results showed that stimulating RLPFC and RMPFC have some interference to the task switching performance.In addition,we found that cTBS stimulated RLPFC significantly increased switching costs(SCs)of the error rates(ERs)when switching to stimulus-oriented(SO)tasks,whereas cTBS stimulated RMPFC to significantly decreased SCs of ERs when switching to stimulus-Independent(SI)task.These findings provide evidence for a differential role of the RLPFC and the RMPFC in executive functions.