Cognitive Neuroscience Talks
Learning motor actions by observing others: The roles of the mirror neuron system and prefrontal cortex
Stefan Vogt and Satomi Higuchi, Department of Psychology, Lancaster University Mirror neurons become activated both during performing actions and whilst observing another individual performing a similar action. Two main functions of these neurons are understanding the actions of others, and, predominantly in humans, imitation. Mirror neurons are thus a crucial building block for social interaction and communication. Are these neurons also involved when novel actions are learned via observing others? In a series of brain imaging studies employing functional magnetic resonance imaging (fMRI), we have explored the role of the mirror neuron system in learning novel actions by observation. Participants were scanned whilst they imitated unfamiliar hand actions (guitar chords). We found (i) that the mirror neuron system is indeed involved in imitation learning, (ii) that it is involved more strongly for novel actions than for familiar actions, and (iii) that the dorsolateral prefrontal cortex (DLPFC) was activated during imitation of novel actions. The DLPFC is a high-level control system which was likely engaging in restructuring the represented motor elements into a complete finger configuration. In a further study we demonstrated that chords can also be learned by pure observation. Participants who benefitted most from this observational practice showed stronger activations in DLPFC as well as in posterior parietal cortex, which most likely engaged in transforming the observed actions into motor and tactile signals. This opens up an interesting avenue for optimising observational learning procedures in sport and rehabilitation of motor function. In ongoing research, we are contrasting the imitation of hand postures with imitating sequences of finger movements and rhythms. Whereas the sequences largely engaged the same cortical regions as the hand postures (mirror neuron system), the rhythms mainly activated the human expressive speech region (‘Broca’s area’). Thus, the primary cortical representation system can vary according to the type of action observed. In addition, DLPFC tended to be less activated for the rhythms than for the sequences and hand postures: one possible explanation is that rhythms are encoded in a specialised system which does require less supervisory control than spatially oriented actions such as postures and sequences.