Electroencephalogram evidence for the activation of human mirror neuron system during the observation of intransitive shadow and line drawing actions

摘要

Previous studies have demonstrated that hand shadows may activate the motor cortex associated with the mirror neuron system in human brain. However, there is no evidence of activity of the human mirror neuron system during the observation of intransitive movements by shadows and line drawings of hands. This study examined the suppression of electroencephalography mu waves (8-13 Hz) induced by observation of stimuli in 18 healthy students. Three stimuli were used: real hand actions, hand shadow actions and actions made by line drawings of hands. The results showed significant desynchronization of the mu rhythm (“mu suppression”) across the sensorimotor cortex (recorded at C3, Cz and C4), the frontal cortex (recorded at F3, Fz and F4) and the central and right posterior parietal cortex (recorded at Pz and P4) under all three conditions. Our experimental findings suggest that the observation of “impoverished hand actions”, such as intransitive movements of shadows and line drawings of hands, is able to activate widespread cortical areas related to the putative human mirror neuron system. Research Highlights (1) We investigate for the first time mirror neuron system activity using electroencephalography and intransitive actions by line drawings and shadows of hands as stimuli. (2) Electroencephalography findings reveal that intransitive movements by sketched fingers activate brain areas where human mirror neurons reside. (3) There is no significant difference in the degree of mu rhythm desynchronization induced by the three conditions: real hand actions, hand shadow actions and line drawing actions. (4) The stimulus color, texture and fill do not affect the extent of mirror neuron activation by an action. Abbreviations MNS, mirror neuron system; EEG, electroencephalogram