The effect of valence and arousal of emotional pictures on EEG activity
【摘要】：正Objective Greenwald and Lang et al.proposed a theory of motivational priming that suggests emotion differentially modulates defensive behaviors.Positive emotion is associated with activation of the appetitive system,and negative emotion is associated with activation of the defensive system.Valence provides an indicator of the motivational system activated,and arousal indicates the level of activation of the system.Phenomenologically,valence is associated with the tone and arousal with the intensity of the emotion.Different brain regions bear different cognition functions,and so does different EEG frequency.In recent reports,emotional arousal was laid more and more emphasis on,but related study was not enough.Methods Fifteen healthy female volunteers(age range 20-30 years) participated in the 2 stages and 8 EEG sessions(separated by 7-8 minutes with continuous EEG recording) experiment.At first stage the subjects were instructed to arte 150 emotional pictures,so these pictures were grouped into arousal higher,arousal normal,arousal lower,valence positive,valence neutral and valence negative.The second stage was EEG experiment.The first 2 sessions were used as baseline:subject was asked to open and close her eyes for 3mininuts separately.The other 6 sessions involved different emotion groups:the subjects were told to see the emotional pictures on the middle of the screen at the same time EEG was recorded.Fast Fourier Transformation analysis was(FFT) performed based on 7 bands spectrum. Results(1) The prefrontal delta EEG exhibiting higher activity in valence than in arousal condition,and lower in both positive and negative valence than the neutral picture.(2) The frontal brain area of theta was higher in low arousal than in high arousal,while both negative and positive valence were lower than the neutral.(3) The posterior beta-1 activity was higher in valence than that in arousal condition.Conclusion Emotional related brain activation can be sensitively differentiated between arousal dimension vs.valence dimension during picture perception.The fine differentiation can be examined further in the levels of arousal and levels of valence.