Processing Of Unattended Changes In Facial Emotions In Healthy And Dysphoria Individuals:A Magnetoencephalography Study

Since the acquisition of emotional information,especially the emotional information of others,is closely related to our life,the process of attentional process for emotional information has been widely concerned.However,it is not known,to what extent,preattentive encoding and change detection of peripherally presented facial emotion is altered in dysphoria,and the changes in the such backgrounds may give us more critical information.Fortunately,the discovery of visual mismatch negative(vMMN)allows us to better study this unattended process,especially this emotional process in ignored condition.In this way,We use magnetoencephalography(MEG)to record automatic brain responses to happy and sad faces in dysphoric and control participants,and compared the results between them.Result:The purpose of the first study is to explore the unattended emotional process of healthy participants on happy and sad faces by MEG measurement and compare the results with previous studies.On the one hand,we verified the repeatability and stability of the paradigm we adopte here in our MEG study with previous EEG.On the other hand,we expand our understanding of unattended emotional process from fear to other negative emotion(sad in our study).The MEG results showed that the unattended emotional process of healthy participants went through three stages,corresponding to three-time windows of M100,M170 and M300 respectively.We can see that,first,compared to the standard stimulus,new stimulus elicit a larger M100.Then,in the bilateral occipital,compared to the standard stimuli,the deviant stimuli induc larger M170.While at the same time,The M170 was modulated by emotion,which show that M170 induce a greater amplitude for sad faces at right temporal compared to happy faces.Finally,at right occipital,deviant and standard stimuli still show difference responses,which reflect by standard stimuli induced larger responses compared to deviant ones.The purpose of the second study is to further explore the processing of the unattended emotional process from healthy participants to dysphoria individuals.The MEG results show that the unattended emotional process of the depressed participants is also corresponding to the three-time windows of M100,M170 and M300.In the first stage,compared to the standard stimuli,deviant stimuli induce a greater M100,which may reflect the early processing of low-level perceptual features of face stimuli.Then,in the second stage,dysphoria participants mainly start to process emotional stimuli,showing a greater amplitude for sad faces at right temporal,while at left occipital,the change detection was also continuing to produce its effect.In the third stage,there is an interaction effect between emotion and stimulus type,which show that the response of the dysphoria participants to sad deviant stimuli are greater than happy deviant and sad standard stimuli.After comparing of the two results,we can see that,the two groups reflect the same patterns on unattended emotional face processing,reflected by three responses of M100,M170 and M300.Enhanced amplitudes to deviant faces,reflecting the magnetic counterpart of the vMMN response are found for all time intervals,indexing deviance detection,even though the faces are presented peripherally and unattended.The M170 peak amplitudes are also modulated by the emotion,response amplitudes being larger to sad faces compared to happy faces.Group differences are found for the M300.In the dysphoric group,at left occipital region of interest,the amplitudes are larger for sad than happy deviant faces,while no such difference was found in the control group.On the other hand,at the right occipital region of interest,the control group show larger M300 amplitudes for deviant compared to standard faces,while no amplitude difference between stimulus types is found in dysphoric group.Conclusion:In conclusion,our results show that the unattended emotional processes of the healthy and dysphoria participant both included three stages,the first two stages correspond to the early processing of the low-level visual features of the stimuli,as well as the processing of the facial structure and emotional information.However,in the third stage,the two groups showed different patterns,which indicate that in dysphoric participants change detection is on the one hand impaired,but on the other hand,particularly sensitive to sad faces,suggesting that negative bias is not exclusive to attentive processing,but extends this effect to preattentive face processing.To sum up,our results indicate that there is a negative bias in automatic visual deviance detection,but also a general change detection deficit in dysphoria.These results may have important effect on,for instance,real-life social interactions,and extend the potential clinical utility of the emotional vMMN to dysphoria individuals.