title: Resonating with the ghost of a hand: A TMS experiment.
abstract: An impressive body of literature in the past 20 years has revealed a possible role played by cortical motor areas in action perception. One question that has been of interest is whether these areas are selectively tuned to process the actions of biological agents. However, no experiments directly testing the effects of the main characteristics identifying a biological agent (physical appearance and movement kinematics) on corticospinal excitability (CS) are present in literature. To fill this gap, we delivered single-pulse transcranial magnetic stimulation to the primary motor cortex and we recorded motor evoked potentials from contralateral hand muscles during observation of point-light-displays stimuli representing a hand having lost its physical appearance (Experiment 1) and kinematics characteristics (Experiment 2). Results showed that physical appearance, natural kinematics, and the possibility to identify the action behind the stimulus are not necessary conditions to modulate CS excitability during stimuli observation. We propose that the involvement of the motor system can be mandatory whenever the perceived movement, executed by a human, by an animal or by an object, is recognized as reproducible in its final outcome (e.g., position in space, direction of movement, posture of a body part, to-be-produced sound, specific interaction with an object, etc.), and that the peculiar relationship existing between others' actions and the actions executed by the observer could just represent the extreme in which the motor system is able to almost perfectly reproduce the observed stimulus as it unfolds and, consequently, contribute to stimulus perception in the most efficient way.
authors.affiliation: Department of Biomedical and Specialty Surgical Sciences, School of Medicine, University of Ferrara, via Fossato di Mortara 19, 44121 Ferrara, Italy. Electronic address: laila.craighero@unife.it.
authors.forename: Laila
authors.initials: L
authors.lastname: Craighero
authors.affiliation: Department of Robotics, Brain and Cognitive Sciences, Istituto Italiano di Tecnologia, via Morego 30, 16163 Genova, Italy. Electronic address: Marco.Jacono@iit.it.
authors.forename: Marco
authors.initials: M
authors.lastname: Jacono
authors.affiliation: Department of Biomedical and Specialty Surgical Sciences, School of Medicine, University of Ferrara, via Fossato di Mortara 19, 44121 Ferrara, Italy. Electronic address: sonia.mele@unife.it.
authors.forename: Sonia
authors.initials: S
authors.lastname: Mele
mesh_terms: D001696:Biomechanical Phenomena / Q000502:physiology; D004576:Electromyography; D019054:Evoked Potentials, Motor; D005260:Female; D006225:Hand / Q000502:physiology*; D006801:Humans; D008297:Male; D009039:Motion Perception / Q000502:physiology*; D009044:Motor Cortex / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology; D009483:Neuropsychological Tests; D010775:Photic Stimulation / Q000379:methods; D050781:Transcranial Magnetic Stimulation / Q000379:methods*; D055815:Young Adult
keywords: Action observation; Biological motion; Point-light-displays; Premotor cortex; Transcranial magnetic stimulation