ИСТИНА

Movement observation (MO) modulates activity of brain regions involved in motor control. It is mentioned that this phenomenon is evoked by the mirror neurons system activity and reflects processes of action understanding, action recognition and covert imitation of observed movements. Desynchronization of sensorimotor EEG oscillations and increase in corticospinal excitability assessed by transcranial magnetic stimulation (TMS) are invasive markers of motor and somatosensory cortices activation. Despite the fact that numerous studies show sensitivity of these markers to movements observation, little is known about the dynamics of the EEG activity and corticospinal excitability during evaluating the anatomically correctness of observed actions. We designed a TMS-EEG experiment with passive observation of simple aimless movements, in which subjects observed natural and unnatural flexions of fingers. Spatially separated sensorimotor EEG oscillations and TMS evoked myographic potentials were studied. The results revealed sensitivity of mu/beta oscillations to the anatomical correctness of movement. No correlations between mu/beta desynchronization and motor evoked potentials (MEPs) were found, but a weak link between beta synchronization and MEPs was shown. It might be proposed that ERD reflects activity of rather somatosensory but not motor cortex. Our findings demonstrate that activity of the sensorimotor cortex is modulated by action observation and action recognition, whereas EEG activity from different frequency ranges is modulated in different ways. Importantly, no significant changes in MEPs amplitude during MO was found. This result is discussed with regard to the impact of experimental instructions and participant's mental state during the MO task.