Effects of brief imitative experience on EEG desynchronization during action observation.

There is a good deal of evidence that observing the actions of other people is associated with activation of the observer's motor system, which may reflect involvement of the mirror neuron system (MNS) in certain aspects of action processing in humans. Furthermore, variation in the extent of this activation appears to be partly dependent on individuals' experience with performing the observed actions. However, very little work has examined the processes through which the observation of unfamiliar actions--which are not in an observer's motor repertoire--might become associated with MNS activation. In the current study we examined differences in EEG desynchronization in alpha-range bands during action observation following very brief imitative experience with the observed actions, which were novel drawing movements. Compared to carrying out unrelated actions, brief imitative experience was specifically associated with a significantly larger desynchronization in the 11-13 Hz band at mid-frontal sites (F3 and F4) when a previously imitated action was viewed again. In addition, higher fidelity of imitation was significantly correlated with greater bilateral desynchronization of the lower mu band (8-10 Hz) at central sites (C3 and C4) during subsequent observation of the previously imitated action. Our findings point to the involvement of frontal cortical processing and the MNS in the early stages of imitative learning.