title: Facilitation of corticospinal connections in able-bodied people and people with central nervous system disorders using eight interventions.
abstract: BACKGROUND
  Voluntary contractions (VOL), functional electrical stimulation (FES), and transcranial magnetic stimulation (TMS) can facilitate corticospinal connections.
  
  
  OBJECTIVE
  To find the best methods for increasing corticospinal excitability by testing eight combinations: (1) VOL, (2) FES, (3) FES + VOL, (4) TMS, (5) TMS + VOL, (6) paired associative stimulation (PAS) consisting of FES + TMS, (7) PAS + VOL, and (8) double-pulse TMS + VOL.
  
  
  METHODS
  Interventions were applied for 3 × 10 minutes in 15 able-bodied subjects, 14 subjects with stable central nervous system lesions (e.g., chronic stroke, and incomplete spinal cord injury) and 16 subjects with progressive central nervous system conditions (e.g., secondary progressive multiple sclerosis). Motor-evoked potentials (MEP), M-waves, and H-reflexes were monitored over a 1-hour period.
  
  
  RESULTS
  Three interventions (PAS, PAS + VOL, and double-pulse TMS + VOL) caused 15% to 20% increases (P < 0.05) in the MEP at a stimulus level that initially produced a half-maximal response (MEP(half)) during a contraction. Interventions were less effective in both clinical groups than in the able-bodied group. Interventions with VOL were more effective in increasing the MEP(half) than those without (P = 0.022). When more modalities were combined, the MEP increases were larger (P = 0.022).
  
  
  CONCLUSIONS
  (1) Short-term application of FES, TMS, and VOL can facilitate corticospinal pathways, particularly when methods are combined. (2) The effects may depend on the total activation of neural pathways, which is reduced in central nervous system disorders.
authors: Department of Physiology, University of Alberta, Edmonton, Canada. richard.stein@ualberta.ca
authors: Richard B
authors: RB
authors: Stein
authors: Dirk G
authors: DG
authors: Everaert
authors: François D
authors: FD
authors: Roy
authors: SuLing
authors: S
authors: Chong
authors: Maryam
authors: M
authors: Soleimani
mesh_terms: D000328:Adult; D000368:Aged; D004558:Electric Stimulation; D004576:Electromyography; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D006181:H-Reflex / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000502:physiology* / Q000503:physiopathology; D009103:Multiple Sclerosis / Q000503:physiopathology; D009119:Muscle Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology* / Q000503:physiopathology; D009473:Neuronal Plasticity / Q000502:physiology*; D011712:Pyramidal Tracts / Q000502:physiology* / Q000503:physiopathology; D013119:Spinal Cord Injuries / Q000503:physiopathology; D020521:Stroke / Q000503:physiopathology; D050781:Transcranial Magnetic Stimulation