EEG Investigation of Mirror-Neuron Activity Before and After Conscious Perception of Emotion in Faces

While it is theorized that the human Mirror Neuron System (MNS) is used in action understanding and interpretation, how mu-wave suppression varies throughout the process of becoming conscious of a human facial expression and perceiving it has not been investigated. In the current study, EEG mu-wave suppression was used as an index of MNS activity. Data were collected while subjects viewed a 6 second clip in which static visual noise lifted over a period of 3 seconds revealing either a sad or angry face below which participants were asked to indicate the emotion with a keyboard button press. The image being revealed examined the mu-wave suppression while starting unconscious and then becoming conscious of a facial emotion. To examine mu-wave suppression once already conscious of a face and the variance of artifact difficulty, the image was then covered with static visual noise over an additional 3 seconds. The mu-wave suppression was modulated most by the conscious decision making of facial perception while it was not strongly modulated by the level of noise. This suggests that the human MNS is utilized when interpreting facial emotions