title: Reduced motor cortex plasticity following inhibitory rTMS in older adults.
abstract: OBJECTIVE
  Ageing is accompanied by diminished practice-dependent plasticity. We investigated the effect of age on another plasticity inducing paradigm, repetitive transcranial magnetic stimulation (rTMS).
  
  
  METHODS
  Healthy young (n=15; 25+/-4 years) and old (n=15; 67+/-5 years) adults participated in two experiments. Motor evoked potentials (MEPs) were measured in the target muscle (first dorsal interosseus, FDI) and a remote muscle (abductor digiti minimi) during a set of single stimuli. Subjects then received real or sham inhibitory rTMS (intermittent subthreshold trains of 6Hz stimulation for 10min). MEPs were measured for 30min after rTMS.
  
  
  RESULTS
  In young adults, MEPs in the target FDI muscle were approximately 15% smaller in the real rTMS experiment than in the sham rTMS experiment (P<0.026). In old adults, FDI MEP size did not differ between experiments.
  
  
  CONCLUSIONS
  Advancing age is associated with reduced efficacy of inhibitory rTMS.
  
  
  CONCLUSIONS
  This work has important implications for the potential therapeutic use of rTMS in stroke and neurological disease.
authors.affiliation: Discipline of Physiology, School of Molecular and Biomedical Science, The University of Adelaide, Adelaide, SA, Australia. gabrielle.todd@adelaide.edu.au
authors.forename: Gabrielle
authors.initials: G
authors.lastname: Todd
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Kimber
authors.forename: Michael C
authors.initials: MC
authors.lastname: Ridding
authors.forename: John G
authors.initials: JG
authors.lastname: Semmler
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D004574:Electromagnetic Fields; D019054:Evoked Potentials, Motor / Q000502:physiology* / Q000528:radiation effects; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000033:anatomy & histology / Q000502:physiology* / Q000528:radiation effects; D009048:Motor Skills / Q000502:physiology / Q000528:radiation effects; D009068:Movement / Q000502:physiology; D009119:Muscle Contraction / Q000502:physiology / Q000528:radiation effects; D018482:Muscle, Skeletal / Q000294:innervation / Q000502:physiology; D009433:Neural Inhibition / Q000502:physiology* / Q000528:radiation effects; D009473:Neuronal Plasticity / Q000502:physiology* / Q000528:radiation effects; D011712:Pyramidal Tracts / Q000502:physiology / Q000528:radiation effects; D011930:Reaction Time / Q000502:physiology; D009435:Synaptic Transmission / Q000502:physiology / Q000528:radiation effects; D050781:Transcranial Magnetic Stimulation / Q000379:methods*; D016896:Treatment Outcome; D055815:Young Adult