EEG evidence for human mirror activity during observation of ambiguous shadow actions: Toward an analysis of humanoid robotic system

In this study, we investigated whether mere observation of ambiguous shadow motions with an anamorphic shape of a real hand would induce the human mirror neuron system (hMNS) activity and which aspects of the observed motion (i.e. the biologic property and the kinematical characteristic) are crucial to the hMNS activity. As an index of hMNS activity, EEG mu rhythm (8-13Hz) suppression at C3, Cz and C4 electrodes was examined during observation of ambiguous shadow motions with pre- and post-familiarisation compared to a flat geometrical shape movement (Baseline). The experimental results showed that no hMNS activity was found in pre-familiarisation condition even the anamorphic shadow was perceived as human hand. While, the hMNS activity was apparently found after a familiarisation process involves learning the kinematics features of the anamorphic shadow. Results reported here suggest that both biologic property and the kinematics features are crucial to the hMNS activity. The findings also may provide a new idea for the development of humanoid robotic system by modeling the human motion as two attribute set: biologic properties and kinematics primaries.