The Effect Of Emotional Faces On Attention Network Based On TMS And FMRI

When we deal with a large amount of visual information,the brain evolves a selective attention mechanism to filter the visual stimulus due to limited cognition resources.The frontoparietal attention network is primarily responsible for this selective attention mechanism.The dorsal network,including frontal eye field and intraparietal sulcus,is driven by current task goal.While the ventral attention network,mainly the inferior frontal gyrus and temporal parietal junction,is more driven by the stimulus itself.When the visual input are emotional faces,the emotional face will be “automatic” processed by visual system,for containing special emotional and social information.However,this "automatic" processing is still mediated by the attention mechanism.The focus of this paper is on the relationship between emotional face network and attention network and their potential connectivity.First of all,we performed Clark and Hillyard's classic spatial attention experiment during MRI scanning.Three kinds of emotional(happy,fearful,neutral)face images were used as the target stimulus and standard stimulus for MRI experiment.18 subjects only responded to the target stimulus at the attended visual side.Behavior and BOLD signal results showed that:(1)For the reaction time of the emotional face,the subjects responded to the emotional face(happy and fearful)faster than the neutral face in the left visual field;for the emotional face,the subjects responded faster in the left visual field than the right visual field for emotional faces.(2)ROI analysis showed: bilateral FEF demonstrated the left visual field advantage for emotional faces,and the bilateral fusiform area(FFA)indicated an attention effect.(3)For Granger causality analysis,the path from right FFA to the right FEF through the left IFF was found to be responsible for the interaction between the face network and the attention network.In the subsequent TMS experiment,we confirmed the relationship between the face network and frontoparietal attention network.We used Posner's spatial attention experiment with the backward masking of emotional faces for our TMS experiment.25 subjects discriminate the emotion content of faces in the cued visual field(whether it is neutral or not).In the cue phase of the experiment,we applied 10 Hz rTMS stimulation over the right IPS,compared to stimulation over vertex.The behavioral results showed that:(1)For the reaction time of the emotional face,the subjects responded to the emotional face(happy and fearful)much faster than the neutral face.(2)The TMS stimulation effect of the right IPS demonstrated a greater impact for the left visual field that the right visual field.(3)The right IPS-TMS stimulation only affected the emotional effect(emotionalneutral)in the left visual field compared to the TMS stimulation of control point.Both MRI experiment and the TMS experiment showed that the interaction between the face network and the attention network existed in the dorsal attention network(FEF and IPS),and the perception advantage of emotional faces existed in the left visual field.The connectivity between right FFA and right FEF probably is responsible for the interaction between two networks.This potential right-lateralized pathway explains the advantages of the left visual field for the emotional face perception...