The Role of the Mirror Neuron System in Motor Learning

Following a classical perspective, acquiring a new motor skill implies moving from a declarative knowledge of the motor task to be learned to a procedural knowledge of it. Some recent research on the motor system challenges this view. In the ventral premotor cortex of a monkey, neurons have been discovered that discharge both when an animal executes a specific goal-directed action (i.e. grasping a piece of food) and when it observes the same or a similar action executed by a conspecific or an experimenter. These neurons are called “mirror neurons”. In humans the mirror neuron system code for the execution and observation of goal-directed actions is executed with different biological effectors like the hand, the mouth, and the foot. The mirror neuron system has been demonstrated to be involved in action recognition, motor imagery and on line imitation of simple movements, which are already present in the motor repertoire of the acting individuals. Furthermore, in a very recent functional magnetic resonance image (fMRI) study, the involvement of this system in learning novel, complex hand actions has been tested. In the experiment musically naïve participants were asked to learn to play different guitar chords, after observing models given by an expert guitarist. The mirror neuron system has been found active in all phases of the motor learning process, namely from the observation of the model till the execution of it by the participants. These results strongly support the notion that learning a new motor pattern implies re-arranging the elementary motor acts constituting it in order to fit a given model. This is an operation that the brain apparently does within the motor system, without the involvement of any specific associative areas.