Crossmodal and action-specific: neuroimaging the human mirror neuron system

• A human mirror neuron system (HMNS) is thought to underpin complex social phenomena.
• Key criteria for HMNS regions are crossmodal and action-specific responses.
• Until recently key criteria remain largely untested in human functional magnetic resonance imaging (fMRI) studies.
• Regions outside the canonical frontoparietal HMNS show ‘mirror’ properties.
• Properties of the HMNS can be studied using multivariate pattern analyses (MVPA).

The notion of a frontoparietal human mirror neuron system (HMNS) has been used to explain a range of social phenomena. However, most human neuroimaging studies of this system do not address critical ‘mirror’ properties: neural representations should be action specific and should generalise across visual and motor modalities. Studies using repetition suppression (RS) and, particularly, multivariate pattern analysis (MVPA) highlight the contribution to action perception of anterior parietal regions. Further, these studies add to mounting evidence that suggests the lateral occipitotemporal cortex plays a role in the HMNS, but they offer less support for the involvement of the premotor cortex. Neuroimaging, particularly through application of MVPA, has the potential to reveal the properties of the HMNS in further detail, which could challenge prevailing views about its neuroanatomical organisation.