title: Modulation of corticospinal excitability by paired associative stimulation: reproducibility of effects and intraindividual reliability.
abstract: OBJECTIVE
  Electrical stimulation of the median nerve followed by a magnetic pulse on the primary motor cortex (M1) is effective to cause an increase in the amplitude of motor evoked potential (MEP) registered in the target muscle with the interstimulus interval (ISI) at 25ms (paired associative stimulation, PAS). The aim of this study is to evaluate the reproducibility of PAS with ISI 25 (PAS25), assessed in two separate sessions. Intraindividual reliability of TMS measures was also evaluated.
  
  
  METHODS
  Motor threshold of abductor pollicis brevis (APB), assessed at rest, and MEP amplitude of APB and abductor digiti minimi (ADM) were assessed before and after PAS25 in 18 healthy volunteers (nine males and nine females).
  
  
  RESULTS
  Data showed a significant increase of MEP amplitude in the target muscle (APB) after PAS25 and a reproducibility of group effect in the two sessions, as assessed by ANOVA, but a lack of intraindividual reliability, as assessed by intraclass correlation coefficients (ICC).
  
  
  CONCLUSIONS
  The results underline the reproducibility of mean effects and the need to be careful when comparing the same subject on different days.
  
  
  CONCLUSIONS
  Electrical stimulation of the median nerve followed by a magnetic pulse delivered on M1 after 25ms causes a reproducible increase in MEP amplitude, without showing an acceptable intraindividual reliability.
authors.affiliation: Department of Psychology, University of Rome, La Sapienza, Rome, Italy.
authors.forename: Fabiana
authors.initials: F
authors.lastname: Fratello
authors.forename: Domenica
authors.initials: D
authors.lastname: Veniero
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Curcio
authors.forename: Michele
authors.initials: M
authors.lastname: Ferrara
authors.forename: Cristina
authors.initials: C
authors.lastname: Marzano
authors.forename: Fabio
authors.initials: F
authors.lastname: Moroni
authors.forename: Maria Concetta
authors.initials: MC
authors.lastname: Pellicciari
authors.forename: Mario
authors.initials: M
authors.lastname: Bertini
authors.forename: Paolo Maria
authors.initials: PM
authors.lastname: Rossini
authors.forename: Luigi
authors.initials: L
authors.lastname: De Gennaro
mesh_terms: D000010:Abducens Nerve / Q000502:physiology / Q000528:radiation effects; D000328:Adult; D000704:Analysis of Variance; D004558:Electric Stimulation; D004576:Electromyography / Q000379:methods; D019054:Evoked Potentials, Motor / Q000502:physiology / Q000528:radiation effects*; D005260:Female; D006801:Humans; D008280:Magnetics; D008297:Male; D009044:Motor Cortex / Q000502:physiology*; D011712:Pyramidal Tracts / Q000502:physiology*; D015203:Reproducibility of Results; D012684:Sensory Thresholds / Q000502:physiology / Q000528:radiation effects; D013223:Statistics as Topic; D050781:Transcranial Magnetic Stimulation