mu and alpha power during action observation

We investigated live and video perception by analyzing EEG oscillations of the sensorimotor (mu-rhythm) and visual (alpha-rhythm) cortex of the brain in an experiment with observation of identical action demonstrators live and on video. The mu-rhythm reflects the activity of the mirror neuron system, which is responsible for social perception of the actions and body language of other people, and the occipital alpha-rhythm shows the level of visual attention. We used 32-channel EEG recorded during live and video action observation in 83 healthy volunteers. The ICA infomax method was used for decomposing and selecting the components of the mu- and alpha-rhythms; the Fourier Transform was used to calculate the suppression index relative to the baseline (stationary demonstrator) of the two sub-bands (8-13 Hz and 13-24 Hz) of the mu-rhythm and the alpha-rhythm. Our work shows that the main range, 8-13 Hz, of the mu-rhythm is indeed sensitive to biological and social movement and is highly dependent on the conditions of interaction - live or video. The upper mu-range of 13-24 Hz appeared to be less sensitive to the type of demonstration, but more sensitive to different movements. The alpha-rhythm does not depend on the type of movement, however, a live performance initially causes a stronger concentration of visual attention. Thus, subtle social and nonverbal perceptions may suffer in remote video interactions.