title: Mental action simulation synchronizes action-observation circuits across individuals.
abstract: A frontoparietal action-observation network (AON) has been proposed to support understanding others' actions and goals. We show that the AON "ticks together" in human subjects who are sharing a third person's feelings. During functional magnetic resonance imaging, 20 volunteers watched movies depicting boxing matches passively or while simulating a prespecified boxer's feelings. Instantaneous intersubject phase synchronization (ISPS) was computed to derive multisubject voxelwise similarity of hemodynamic activity and inter-area functional connectivity. During passive viewing, subjects' brain activity was synchronized in sensory projection and posterior temporal cortices. Simulation induced widespread increase of ISPS in the AON (premotor, posterior parietal, and superior temporal cortices), primary and secondary somatosensory cortices, and the dorsal attention circuits (frontal eye fields, intraparietal sulcus). Moreover, interconnectivity of these regions strengthened during simulation. We propose that sharing a third person's feelings synchronizes the observer's own brain mechanisms supporting sensations and motor planning, thereby likely promoting mutual understanding.
authors.affiliation: Department of Biomedical Engineering and Computational Science, Brain Research Unit, O.V. Lounasmaa Laboratory, and Advanced Magnetic Imaging Centre, Aalto NeuroImaging, Aalto University, FI-0076 Espoo, Finland, and Turku PET Centre, FI-20520 Turku, Finland.
authors.forename: Lauri
authors.initials: L
authors.lastname: Nummenmaa
authors.forename: Dmitry
authors.initials: D
authors.lastname: Smirnov
authors.forename: Juha M
authors.initials: JM
authors.lastname: Lahnakoski
authors.forename: Enrico
authors.initials: E
authors.lastname: Glerean
authors.forename: Iiro P
authors.initials: IP
authors.lastname: Jääskeläinen
authors.forename: Mikko
authors.initials: M
authors.lastname: Sams
authors.forename: Riitta
authors.initials: R
authors.lastname: Hari
mesh_terms: D000328:Adult; D001921:Brain / Q000502:physiology*; D004644:Emotions / Q000502:physiology*; D005260:Female; D006801:Humans; D007206:Individuality; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008606:Mental Processes / Q000502:physiology*; D008875:Middle Aged; D009415:Nerve Net / Q000502:physiology*; D064887:Observational Studies as Topic; D010775:Photic Stimulation / Q000379:methods*; D055815:Young Adult
keywords: action; emotion; mirroring; simulation; somatosensation; synchronization