title: Changing ideas about others' intentions: updating prior expectations tunes activity in the human motor system.
abstract: Predicting intentions from observing another agent's behaviours is often thought to depend on motor resonance - i.e., the motor system's response to a perceived movement by the activation of its stored motor counterpart, but observers might also rely on prior expectations, especially when actions take place in perceptually uncertain situations. Here we assessed motor resonance during an action prediction task using transcranial magnetic stimulation to probe corticospinal excitability (CSE) and report that experimentally-induced updates in observers' prior expectations modulate CSE when predictions are made under situations of perceptual uncertainty. We show that prior expectations are updated on the basis of both biomechanical and probabilistic prior information and that the magnitude of the CSE modulation observed across participants is explained by the magnitude of change in their prior expectations. These findings provide the first evidence that when observers predict others' intentions, motor resonance mechanisms adapt to changes in their prior expectations. We propose that this adaptive adjustment might reflect a regulatory control mechanism that shares some similarities with that observed during action selection. Such a mechanism could help arbitrate the competition between biomechanical and probabilistic prior information when appropriate for prediction.
authors.affiliation: Evolution and Social Cognition Group, Laboratoire de Neurosciences Cognitives (LNC), Département d'Etudes Cognitives, INSERM U960, Ecole Normale Supérieure, PSL Research University, F-75005 Paris, France.|Evolution and Social Cognition Group, Institut Jean Nicod, Département d'Etudes Cognitives, CNRS UMR8129, Ecole Normale Supérieure, PSL Research University, F-75005 Paris, France.
authors.forename: Pierre O
authors.initials: PO
authors.lastname: Jacquet
authors.affiliation: Dynamique Du Langage, CNRS UMR 5596, University Lumières Lyon II, 69363 Lyon, France.
authors.forename: Alice C
authors.initials: AC
authors.lastname: Roy
authors.affiliation: Evolution and Social Cognition Group, Institut Jean Nicod, Département d'Etudes Cognitives, CNRS UMR8129, Ecole Normale Supérieure, PSL Research University, F-75005 Paris, France.|Department of Neuroscience, Biotech Campus-University of Geneva, 1211 Geneva, Switzerland.
authors.forename: Valérian
authors.initials: V
authors.lastname: Chambon
authors.affiliation: Department of Psychology, Bologna University, 40127 Bologna, Italy.|Institute of Sciences and Technologies of Cognition, CNR, 00185 Rome, Italy.
authors.forename: Anna M
authors.initials: AM
authors.lastname: Borghi
authors.affiliation: ImpAct Team, Lyon Neuroscience Research Center CRNL, INSERM U1028, CNRS UMR5292, &Hospices Civils de Lyon, Neuro-immersion &Mouvement et Handicap, 69675 Bron, France.|University Claude Bernard Lyon I, 69100 Villeurbanne, France.
authors.forename: Roméo
authors.initials: R
authors.lastname: Salemme
authors.affiliation: ImpAct Team, Lyon Neuroscience Research Center CRNL, INSERM U1028, CNRS UMR5292, &Hospices Civils de Lyon, Neuro-immersion &Mouvement et Handicap, 69675 Bron, France.|University Claude Bernard Lyon I, 69100 Villeurbanne, France.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Farnè
authors.affiliation: ImpAct Team, Lyon Neuroscience Research Center CRNL, INSERM U1028, CNRS UMR5292, &Hospices Civils de Lyon, Neuro-immersion &Mouvement et Handicap, 69675 Bron, France.|University Claude Bernard Lyon I, 69100 Villeurbanne, France.
authors.forename: Karen T
authors.initials: KT
authors.lastname: Reilly
mesh_terms: D000328:Adult; D059031:Anticipation, Psychological / Q000502:physiology*; D001696:Biomechanical Phenomena; D004576:Electromyography; D019054:Evoked Potentials, Motor / Q000502:physiology; D005260:Female; D006801:Humans; D033182:Intention; D008297:Male; D011939:Mental Recall / Q000502:physiology*; D009039:Motion Perception / Q000502:physiology*; D009043:Motor Activity / Q000502:physiology*; D011712:Pyramidal Tracts / Q000502:physiology*; D050781:Transcranial Magnetic Stimulation