title: The time course of motor cortex plasticity after spaced motor practice.
abstract: BACKGROUND
  Motor learning takes place in several phases. Animal experiments suggest that synaptic plasticity plays an important role in acquisition of motor skills, whereas retention of motor performance is most likely achieved by other mechanisms.
  
  
  OBJECTIVE
  This study compared two spacing approaches and investigated the time course of synaptic plasticity after spaced motor practice (MP).
  
  
  METHODS
  Twenty subjects performed a ballistic thumb flexion task in sessions of 6 × 10 minutes or 12 × 5 minutes. We measured peak acceleration of the target movement throughout the experiment and cortical excitability more than 60 minutes after MP via transcranial magnetic stimulation (TMS). After a retention period, both parameters were re-evaluated.
  
  
  RESULTS
  Mean peak acceleration of the target movement significantly increased (6 × 10 minutes: 21.61 m/s(2) versus 30.80 m/s(2), P = .002; 12 × 5 minutes: 18.52 m/s(2) versus 29.65 m/s(2), P = .01). In both training groups, motor evoked potential (MEP) amplitudes of the trained muscle continuously increased after MP (6 × 10 min: 0.93 mV versus 1.57 mV, P = .19; 12 × 5 min: 0.90 mV versus 1.76 mV, P = .004). After the retention period, motor performance was still significantly enhanced, whereas MEP amplitudes were no longer significantly increased.
  
  
  CONCLUSIONS
  These findings do not provide evidence that in small scale motor learning the duration of practice and rest influences behavioral improvement or induction of cortical plasticity. Our study demonstrates that cortical plasticity after MP displays a dynamical time course that might be caused by different mechanisms.
authors.affiliation: Division of Neuropaediatrics and Muscular Disorders, Department of Paediatrics and Adolescent Medicine, University Medical Centre Freiburg, Germany.
authors.forename: Igor
authors.initials: I
authors.lastname: Delvendahl
authors.forename: Nicola G
authors.initials: NG
authors.lastname: Kuhnke
authors.forename: Nikolai H
authors.initials: NH
authors.lastname: Jung
authors.forename: Florian
authors.initials: F
authors.lastname: Mainberger
authors.forename: Matthias
authors.initials: M
authors.lastname: Cronjaeger
authors.forename: Josef
authors.initials: J
authors.lastname: Unterrainer
authors.forename: Dieter
authors.initials: D
authors.lastname: Hauschke
authors.forename: Volker
authors.initials: V
authors.lastname: Mall
mesh_terms: D000328:Adult; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D009044:Motor Cortex / Q000502:physiology*; D009048:Motor Skills / Q000502:physiology*; D009473:Neuronal Plasticity / Q000502:physiology*; D011214:Practice, Psychological; D050781:Transcranial Magnetic Stimulation