title: Evaluating developmental motor plasticity with paired afferent stimulation.
abstract: OBJECTIVE
  Brain plasticity mechanisms are probably different in children but remain poorly understood. Paired afferent stimulation (PAS) combines peripheral sensory stimulation with transcranial magnetic stimulation (TMS) of primary motor cortex to induce rapid, reversible, topographically specific increases in primary motor cortex excitability suggestive of long-term potentiation in adults. Our aim was to determine frequency, characteristics, age effects, and reproducibility of PAS in school-age children.
  
  
  METHODS
  Typically developing right-handed children (6-18y) were recruited. Median nerve stimulation was delivered 25ms before suprathreshold primary motor cortex stimulation (0.2Hz, 7.5min). Primary outcome was changed in the amplitude of motor evoked potentials (MEPs) at five time points after PAS (0, 15, 30, 45, 75min) expressed as area under the curve. Reproducibility was evaluated. Secondary outcomes included stimulus response curves and safety/tolerability.
  
  
  RESULTS
  Of 28 children (20 males, mean age 12y), 64% demonstrated PAS effects (11 definite, seven probable). PAS effects were sustained across all time points to 75min (p=0.004). Stimulus response curve scores increased after PAS (n=9, p=0.02). PAS effect and age were not correlated. PAS was highly reproducible (p=0.925, r=0.283). Tolerability was favorable without adverse events.
  
  
  CONCLUSIONS
  PAS effects are present and reproducible in children. Pediatric PAS paradigms appear safe and tolerable. PAS may provide insight into endogenous developmental plasticity, informing future studies in children with cerebral palsy and other motor disorders.
authors: Department of Neurosciences, University of Calgary, Calgary, AB, Canada.|Calgary Pediatric Stroke Program, University of Calgary, Calgary, AB, Canada.|Alberta Children's Hospital Research Institute, Calgary, AB, Canada.
authors: Omar
authors: O
authors: Damji
authors: Calgary Pediatric Stroke Program, University of Calgary, Calgary, AB, Canada.|Alberta Children's Hospital Research Institute, Calgary, AB, Canada.
authors: Jamie
authors: J
authors: Keess
authors: Calgary Pediatric Stroke Program, University of Calgary, Calgary, AB, Canada.|Alberta Children's Hospital Research Institute, Calgary, AB, Canada.|Department of Pediatrics and Clinical Neurosciences, University of Calgary, Calgary, AB, Canada.
authors: Adam
authors: A
authors: Kirton
mesh_terms: D000293:Adolescent; D000344:Afferent Pathways / Q000502:physiology; D002648:Child; D002657:Child Development / Q000502:physiology*; D004558:Electric Stimulation; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008475:Median Nerve / Q000502:physiology; D009044:Motor Cortex / Q000502:physiology*; D009473:Neuronal Plasticity / Q000502:physiology*; D010525:Peripheral Nerves / Q000502:physiology*; D015203:Reproducibility of Results; D050781:Transcranial Magnetic Stimulation