title: The Relative Influence of Goal and Kinematics on Corticospinal Excitability Depends on the Information Provided to the Observer.
abstract: Viewing a person perform an action activates the observer's motor system. Whether this phenomenon reflects the action's kinematics or its final goal remains a matter of debate. One alternative to this apparent controversy is that the relative influence of goal and kinematics depends on the information available to the observer. Here, we addressed this possibility. For this purpose, we measured corticospinal excitability (CSE) while subjects viewed 3 different grasping actions with 2 goals: a large and a small object. Actions were directed to the large object, the small object, or corrected online in which case the goal switched during the movement. We first determined the kinematics and dynamics of the 3 actions during execution. This information was used in 2 other experiments to measure CSE while observers viewed videos of the same actions. CSE was recorded prior to movement onset and at 3 time points during the observed action. To discern between goal and kinematics, information about the goal was manipulated across experiments. We found that the goal influenced CSE only when its identity was known before movement onset. In contrast, a kinematic modulation of CSE was observed whether or not information regarding the goal was provided.
authors.affiliation: Department of Physiology and Biophysics, School of Medicine, University of Buenos Aires, Buenos Aires C1121ABG, Argentina.
authors.forename: Sofía I
authors.initials: SI
authors.lastname: Mc Cabe
authors.affiliation: Department of Physiology and Biophysics, School of Medicine, University of Buenos Aires, Buenos Aires C1121ABG, Argentina.
authors.forename: Jorge Ignacio
authors.initials: JI
authors.lastname: Villalta
authors.affiliation: Centro de Ciências da Saúde, Laboratorio de Neurobiologia II, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Ghislain
authors.initials: G
authors.lastname: Saunier
authors.affiliation: Department of Psychology, University of California, Santa Barbara, CA, USA.
authors.forename: Scott T
authors.initials: ST
authors.lastname: Grafton
authors.affiliation: Department of Physiology and Biophysics, School of Medicine, University of Buenos Aires, Buenos Aires C1121ABG, Argentina.
authors.forename: Valeria
authors.initials: V
authors.lastname: Della-Maggiore
mesh_terms: D000328:Adult; D001132:Arm / Q000502:physiology; D001696:Biomechanical Phenomena; D004576:Electromyography; D005260:Female; D006040:Goals; D006801:Humans; D008297:Male; D009039:Motion Perception / Q000502:physiology*; D009043:Motor Activity / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology; D010775:Photic Stimulation; D011712:Pyramidal Tracts / Q000502:physiology; D050781:Transcranial Magnetic Stimulation; D014741:Video Recording; D055815:Young Adult
keywords: action observation; corticospinal excitability; goal; kinematics; motor facilitation; transcranial magnetic stimulation