title: The effects of expectancy on corticospinal excitability: passively preparing to observe a movement.
abstract: The corticospinal tract excitability is modulated when preparing movements. Earlier to movement execution, the excitability of the spinal cord increases waiting for supraspinal commands to release the movement. Movement execution and movement observation share processes within the motor system, although movement observation research has focused on processes later to movement onset. We used single and paired pulse transcranial magnetic stimulation on M1 (n = 12), and electrical cervicomedullary stimulation (n = 7), to understand the modulation of the corticospinal system during the "preparation" to observe a third person's movement. Subjects passively observed a hand that would remain still or make an index finger extension. The observer's corticospinal excitability rose when "expecting to see a movement" vs. when "expecting to see a still hand." The modulation took origin at a spinal level and not at the corticocortical networks explored. We conclude that expectancy of seeing movements increases the excitability of the spinal cord.
authors.affiliation: Laboratory of Neuroscience and Motor Control (NEUROcom), Department of Medicine-INEF-Galicia and Institute of Biomedical Research of Coruña, University of A Coruña, A Coruña, Spain;
authors.forename: Pablo
authors.initials: P
authors.lastname: Arias
authors.forename: Verónica
authors.initials: V
authors.lastname: Robles-García
authors.forename: Nelson
authors.initials: N
authors.lastname: Espinosa
authors.forename: Yoanna
authors.initials: Y
authors.lastname: Corral-Bergantiños
authors.forename: Laura
authors.initials: L
authors.lastname: Mordillo-Mateos
authors.forename: Kenneth
authors.initials: K
authors.lastname: Grieve
authors.forename: Antonio
authors.initials: A
authors.lastname: Oliviero
authors.forename: Javier
authors.initials: J
authors.lastname: Cudeiro
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001288:Attention / Q000502:physiology*; D004576:Electromyography; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D006225:Hand / Q000502:physiology; D006801:Humans; D008297:Male; D009039:Motion Perception / Q000502:physiology; D009068:Movement / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology; D019370:Observation; D010775:Photic Stimulation; D011712:Pyramidal Tracts / Q000502:physiology*; D050781:Transcranial Magnetic Stimulation; D055815:Young Adult
keywords: TMS; cervicomedullary stimulation; corticospinal excitability; movement observation; movement preparation; spinal excitability