Study Of FEF In Color And Motion Featured Attention Based On TMS

Visual attention is defined as the direction and concentration of mental activities or consciousness on certain things,coordinated with memory and thinking,to complete the basic daily neural cognitive process.Previous studies have suggested that the Frontal Eye Field(FEF)is one of the most important brain areas which involved in visual attention,together with the posterior parietal cortex and ventral prefrontal cortex to form the neural pathways of visual attention.Other studies showed that the functional impairment of FEF is closely related to many clinical diseases such as attention deficit disorders.Therefore,the study of FEF is of great importance to neurocognitive and clinical diseases.Visual attention can be divided to visual spatial attention and visual feature attention.One of them,visual feature attention is a process of selective attention to a specific feature from different feature information.In recent years,most of the researches on FEF focus on visual spatial attention,and the studies of FEF during visual feature attention are quite poor.Therefore,this paper mainly designed the visual attention task with color and motion dual features,and studied the role of FEF during this process.In recent years,Transcranial Magnetic Stimulation(TMS),as a safe physical stimulation method,has been widely used in various neural-related studies.In this study,the physical intervention method of single pulse TMS was applied and experimental platform was build which based on TMS synchronization measurement.The present study also designed a visual attention task paradigm based on color and motion features with cue information,and carried out two relatively independent experimental processes,FEF's action time in the process of visual feature attention and the conduction mechanism of FEF's neural activity in the process of visual attention were studied respectively.First,in order to study the effect time of FEF during visual feature attention,the single pulse TMS which above the stimulus threshold was applied to the right FEF as a means of interference,and the experimental groups was designed by comparing with TMS on the vertex.The results of research showed that stimulation of different brain regions had no significant effect on response accuracy of subjects.And for the subjects'response time,As TMS acted on FEF,response time increased significantly which compared to the vertex group.The results illustrated that FEF was disturbed by TMS,and which affected the subjects' judgment of the visual attention task,it also proved that FEF was an important brain region which was involved in visual featured attention.Besides,different time points of TMS stimulation were designed in this study and experimental group were conducted on Oms,50ms,100ms,150ms and 200ms of video stimulation during the visual feature attention.The results of study showed that when the TMS stimulation time was 100ms,and TMS was applied on right FEF,the response time of the subjects was significantly higher than that of TMS on vertex.The results indicated that FEF is disturbed by TMS at this time,which also affected the subjects' response time in the visual featured attention task.Therefore,FEF's effect time during the visual attention process is about 100ms from the beginning of visual stimulus.Based on the effect time of FEF,the research further explored the transmission mechanism of FEF neural activity in the process of visual feature attention.In this study,the stimulation parameters of TMS were set as the single-pulse which below the stimulus threshold and as the probe method,the TMS did not change the neural function of the target brain area of the stimulation,and only had the superposition effect of neural activity on the stimulation brain area,and the study explored the transmission mechanism of FEF's neural activity by analyzing the superposition EEG signals stimulated brain region.The stimulation time of TMS was set at 100ms from the beginning of video stimulation during visual feature attention,which is the action time of FEF,to maximize the neural activity of FEF to analysis its neural signals transmission.Subsequently,the transmission direction of FEF's neural activity and the difference in the transmission of FEF's neural activity during visual featured attention between color and motion were studied.The study analyzed the neural activity of TMS superimposed on the brain region(FEF).Results showed that signal amplitude of FC4(around FEF)after the TMS had a tendency to rise,while the signals which located in the parietal lobe and the regions that after the parietal lobe also had a similar trend,however,relative to FC4,this trend had a delay which about 50ms.And during the delay period of signal amplitudes,FC4 with multiple posterior electrodes of the brain areas had significant correlation,and results on scalp and cortex both showed that during the period,neural activity of FEF has the trend which from the front(frontal lobe)passed to back(parietal lobe and posterior areas).Therefore,the study suggested that the neural activity of FEF during the early stage of visual featured attention was transmitted to the posterior brain region.In addition,the study was also analyzed on the FEF's neural activity transmission during different processes of color and motion featured attention.It is found that the posterior brain region has certain differences in FEF's signal transmission,and the brain regions for color information processing is mainly located in the posterior parietal lobe brain region,while the brain regions for motion information processing is mainly located near the parietal and temporal junction.It indicated that FEF may have a certain neural control effect on the selection of different features in the process of visual featured attention,and different features correspond to different brain regions during information processing.In this study,single pulse TMS with different stimulus parameters were used and the corresponding experimental processes was designed,the results not only obtained the action time of FEF in visual feature attention process,but also proved the conduction direction of FEF's nerve activity in the process.The application of single pulse TMS provided a direct and effective method for the study of FEF's role in visual attention.Then,the study of TMS combined with EEG signal had a high temporal accuracy,which can provide stronger evidence for the researches on the transmission mechanism of neural signals during the visual featured attention in the time domain,and also provide an effective method for related researches on neural cognition.