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

P300 in Event-Related Potential(ERP)can reflect the psychological process of resource allocation and assessment,as well as the update process of decision-making and memory.Studies have shown that the source of P300 includes the frontal lobe,parietal lobe,temporal lobe,cingulate gyrus,hippocampus and other brain regions.Visual target search can cause more obvious P300 components,and studies have also found that aging,schizophrenia,depression and other neuropsychiatric diseases can cause significant abnormalities in P300 components.Therefore,the traceability analysis of P300 plays an important role in understanding the occurrence mechanism of these diseases.This paper adopted the visual search paradigm,including pop-out task and search task,in which the color of target stimulus and interference stimulus is different in popout task,and the orientation of target stimulus and interference stimulus is only different in search task.Specific research content included: 1.Functional magnetic resonance imaging(fMRI)and ERP fusion were used to identify the possible source areas of P300 production.2.Because of the characteristic time window of P300,transcranial magnetic stimulation was used to intervene at different time points(0,100,200,300 ms)after the stimulation.The brain area of intervention was P300 source localization brain area,and the source area of P300 was further verified from the time characteristics.ERP-fMRI results: ERP results showed that P300 was mainly concentrated in the middle parietal region.The activation under pop-out condition was significantly greater than the search condition.The ERP differential traceability analysis mainly activated the frontal lobe,parietal lobe,temporal lobe,occipital lobe,and medial lateral sulcus;The fMRI results showed that the activated brain areas under pop-out>search included parietal lobe,frontal lobe,temporal lobe and some marginal regions;The results of EEG and fMRI fusion showed that left/right orbital superior frontal gyrus,middle frontal gyrus,left/right middle temporal gyrus,left superior temporal gyrus,right angular gyrus,left central sulcus cover,right posterior central gyrus,left angular gyrus and hippocampus were the source areas of P300 production.Therefore,in the TMS study,the right dorsolateral prefrontal lobe and the right superior lobule were selected as the brain regions of interest.TMS results: when the stimulation mode was three pulses,the TMS stimulation SPL site interfered with the performance of the search task in the 300 ms time window and reduced the accuracy of the subjects;When the stimulation mode was single pulse,it had an inhibitory effect on CZ.The TMS stimulation CZ site interfered with the performance of the search task at the start time window,which reduced the accuracy of the subject.When the TMS stimulated DLPFC at a time window of 100 ms,300 ms,a significant increase of reaction time(RTs)was observed in the pop-out condition.Under search condition,TMS stimulated DLPFC at a time window of 100 ms,and RTs were longer.The above results indicated that TMS stimulation of DLPFC and SPL brain regions is influential under different time windows.Conclusion: ERP-fMRI technique suggests that P300 sources mainly include left/right orbital superior frontal gyrus,middle frontal gyrus,left/right middle temporal gyrus,left superior temporal gyrus,right angular gyrus,left central sulcus cover,right posterior central gyrus,left angular gyrus and hippocampus.The TMS technology further supports the specific performance of the right SPL in the P300 time window.