title: Movement observation-induced modulation of pain perception and motor cortex excitability.
abstract: OBJECTIVE
  The observation of movements increases primary motor cortex (M1) excitability. This exploratory study examined the effects of movement observation on pressure pain threshold (PPT) and transcranial magnetic stimulation (TMS)-indexed corticospinal excitability bilaterally.
  
  
  METHODS
  Thirty healthy right-handed subjects were randomized to a left hand-movement observation task or a control task. Statistical analyses were performed using ANOVA models and t-tests. Results were not corrected for multiple comparisons. Quantitative sensory assessments were measured in both hands, while M1 excitability has only been tested for the right (non-dominant) M1 corresponding to the observed left hand movements.
  
  
  RESULTS
  Analysis of pain and cortical silent period (CSP) outcomes demonstrated a significant interaction between task (hand-movement group) versus control group and time (pre-/postintervention). PPT increased in the left hand (moving hand in the task) and declined significantly in the contralateral hand (still hand) in the movement-observation-task-group, whereas PTT in the control group remained unchanged. CSP was significantly shorter in the movement-observation group indicating decreased intracortical inhibition (results uncorrected for multiple comparisons).
  
  
  CONCLUSIONS
  The observation of hand-movements led to a side-specific reduction in pain perception and a decrease in intracortical inhibition.
  
  
  CONCLUSIONS
  These exploratory findings support the notion that M1 is a robust modulator of pain-related neural networks. This effect might be mediated through modulation of the GABAergic system and appears to differ from what is observed in chronic pain.
authors.affiliation: Spaulding Neuromodulation Center, Department of Physical Medicine & Rehabilitation, Spaulding Rehabilitation Hospital and Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA; Charité - Universitätsmedizin Berlin, Germany.
authors.forename: Magdalena Sarah
authors.initials: MS
authors.lastname: Volz
authors.affiliation: Spaulding Neuromodulation Center, Department of Physical Medicine & Rehabilitation, Spaulding Rehabilitation Hospital and Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Suarez-Contreras
authors.affiliation: Spaulding Neuromodulation Center, Department of Physical Medicine & Rehabilitation, Spaulding Rehabilitation Hospital and Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
authors.forename: Andrea L Santos
authors.initials: ALS
authors.lastname: Portilla
authors.affiliation: Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA.
authors.forename: Ben
authors.initials: B
authors.lastname: Illigens
authors.affiliation: Charité - Universitätsmedizin Berlin, Germany.
authors.forename: Felix
authors.initials: F
authors.lastname: Bermpohl
authors.affiliation: Spaulding Neuromodulation Center, Department of Physical Medicine & Rehabilitation, Spaulding Rehabilitation Hospital and Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA; Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA; NEC, Psychology Institute, University of Sao Paulo, Sao Paulo, Brazil. Electronic address: fregni.felipe@mgh.harvard.edu.
authors.forename: Felipe
authors.initials: F
authors.lastname: Fregni
mesh_terms: D000293:Adolescent; D000328:Adult; D004311:Double-Blind Method; D019054:Evoked Potentials, Motor / Q000502:physiology*; D006225:Hand / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000502:physiology*; D009068:Movement / Q000502:physiology*; D058748:Pain Perception / Q000502:physiology*; D017288:Pain Threshold / Q000502:physiology; D010775:Photic Stimulation / Q000379:methods*; D050781:Transcranial Magnetic Stimulation / Q000379:methods; D055815:Young Adult
keywords: Corticospinal excitability; M1; Motor cortex; Movement observation; Pain