Mirrors in the Brain
Humans have a remarkable ability to understand the actions and intentions of other people, and to imitate these same actions. How we understand and interpret the actions and an emotion of others has been a central question in neuroscience. Advances in neuroscience in the last decade have led to the discovery of new class of brain cells called mirror neurons. These cells not only fire when we perform an action but also when we watch someone else performing the same action. This discovery has generated tremendous excitement as some scientists speculate that the mirror neuron system may form the basis of our social behaviour, our ability to imitate, acquire language and show empathy.
We recently studied the temporal dynamics and spatial distribution of electroencephalography (EEG) brain responses in young infants during the observation of three distinct types of actions: (a) actions that are within the motor repertoire of infants, (b) actions that are not within the motor repertoire of infants, and (c) object motion. We show that young infants had significant motor resonance to all types of actions in the sensorimotor regions. Only observation of human goal-directed actions led to significant responses in the parietal regions. Importantly, there was no significant mu desychronization observed in the temporal regions under any observation condition. In addition, the onset of mu desychronization occurred earliest in response to object motion, followed by reaching, and finally walking.
Our results suggest that the infants may have a basic, experience-independent sensorimotor mechanism optimized to detect all coherent motion that is modulated by experience.
Virji-Babul et al (2012): Neural correlates of action understanding in infants: influence of motor experience