Study On The Relationship Between Smooth Pursuit Eye Movements And Attention Using TMS

Smooth pursuit is a type of eye movement that eyes follow a moving target,maintaining interesting object on the fovea.There is a close relationship between smooth pursuit eye movements and attention,and research have found that frontal and parietal cortex plays a significant role in attentional control.However,the neural mechanisms of smooth pursuit eye movements are mostly electrophysiological studies of non-human primates,research on the neural mechanisms of human brain is still in the development stage.Furthermore,the relationship between smooth pursuit eye movement and attention is mostly based on psychophysical methods,so it is lack of the study of neural mechanism.The present study combined with transcranial magnetic stimulation(TMS)and eye movement technique,we designed three experiments,adopting continuous theta-burst stimulation(cTBS)in offline pattern,stimulating over frontal eye area,posterior parietal cortex and the control points,then collecting and analyzing the eye movement data,investigating the role of regions of interest in smooth pursuit eye movements and attention.In first experiment,attention resource which required in smooth pursuit is adjusted by controlling the change of the motion signal,namely adopting visual stimuli with different motion information to drive smooth pursuit.The results showed that cTBS over right PPC would reduce the difference which caused by attentional demand in the performance of smooth pursuit,promoting the release of attentional resources in smooth pursuit eye movements,making attentional resources required for the two driving stimuli decrease.However,the right FEF in this experimental paradigm was less affected by cTBS.In order to solve the problem that attention was not directly measured in the first experiment,the second experiment added recognition task in smooth pursuit,and used double-task paradigm to investigate.Results indicated that cTBS over right PPC and right FEF,compared with vertex,delayed the ipsiversive smooth pursuit,which indicated that the stimulation on right PPC and right FEF accelerate the release of attention during ipsiversive smooth pursuit.Previous studies have suggested that the disappearance of foveal stimuli may contribute to the release of attention,and in third experiment we investigated the effect of PPC on the release of attention caused by the disappearance of foveal stimuli.In the experiment,we designed foveal stimulation disappeared 0ms(no-gap)or 200ms(gap)before the target changed in attention task,and combined target detection task.It was found that cTBS over right PPC reduced the difference of pursuit direction in velocity gain during steady state,which tended to increase the velocity gain in rightward pursuit and might facilitate the release of attentional resources during ipsilateral pursuit.For the velocity gain during 700 ms from gap onset,stimulating right PPC increased the difference between no-gap and gap in velocity gain,promoting the modulation of attention resources by foveal stimuli,making gap effect large.In short,PPC plays a promoting role in smooth pursuit eye movement and attention,and although FEF also facilitates the release of attention during ipsiversive smooth pursuit,the neural mechanism of which needs to be further studied.