title: Normative data of cortical excitability measurements obtained by transcranial magnetic stimulation in healthy subjects.
abstract: BACKGROUND
  The assessment of cortical excitability (CE) measurements has been increasingly used in neuropsychiatric research. However, there is scant information on the normative values of these measurements, as well as the possible effect of hemisphere laterality, gender and age on these variables.
  
  
  OBJECTIVE
  To obtain normative data for CE measurements by transcranial magnetic stimulation, to assess inter-/intra-investigator variability and the influence of sex, age and oral contraception use.
  
  
  METHODS
  A sample of 216 healthy volunteers matched according to age and gender was evaluated. Bilateral rest motor thresholds, motor evoked potentials (MEP), intracortical inhibition and facilitation were measured in the first dorsal interosseous muscle area representation of the primary motor cortex with a circular transcranial magnetic stimulation coil delivering biphasic pulses. Normative data were obtained for 200 participants (in a 1:1 male:female ratio) in a balanced proportion between five age groups (18-30; 31-40; 41-50; 51-60; >60 years). Inter/intra-investigator variability was assessed in 20 healthy volunteers in two sessions performed within a 30-minute interval. Measurements were also performed in a subgroup of 16 healthy female volunteers, using oral contraception and during the menstrual phase.
  
  
  RESULTS
  Age had a dichotomous effect on CE measurements, providing significantly different normative data for subjects <50 and >50 years old, with smaller MEP's and intracortical inhibition in older individuals. There were no differences between genders or between left and right hemispheres. Also, CE parameters did not significantly differ with use of contraceptive treatment compared to the menstrual phase of the cycle. The inter-/intra-investigator reliability assessment showed some variability that may not be clinically significant.
  
  
  CONCLUSIONS
  Age had a non-linear effect on CE. There were non-significant differences between genders, hemispheres or with use of oral contraceptives. There was good inter-/intra-investigator correlation for rest motor thresholds and motor evoked potentials while intracortical inhibition and facilitation had low correlations but acceptable reliability.
authors.affiliation: University of São Paulo, Department of Neurology, Pain Center, São Paulo, Brazil; Instituto do Câncer do Estado de São Paulo, Octavio Frias de Oliveira, Pain Center, São Paulo, Brazil.
authors.forename: Ana Sofia
authors.initials: AS
authors.lastname: Cueva
authors.affiliation: University of São Paulo, Department of Neurology, Pain Center, São Paulo, Brazil; University of São Paulo, Department and Institute of Psychiatry, Service of Interdisciplinary Neuromodulation (SIN), São Paulo, Brazil.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Galhardoni
authors.affiliation: University of São Paulo, Department of Neurology, Pain Center, São Paulo, Brazil; Instituto do Câncer do Estado de São Paulo, Octavio Frias de Oliveira, Pain Center, São Paulo, Brazil.
authors.forename: Rubens Gisbert
authors.initials: RG
authors.lastname: Cury
authors.affiliation: University of São Paulo, Department of Neurology, Pain Center, São Paulo, Brazil; Instituto do Câncer do Estado de São Paulo, Octavio Frias de Oliveira, Pain Center, São Paulo, Brazil.
authors.forename: Daniella Cardoso
authors.initials: DC
authors.lastname: Parravano
authors.affiliation: University of São Paulo, School of Medicine, São Paulo, Brazil.
authors.forename: Guilherme
authors.initials: G
authors.lastname: Correa
authors.affiliation: University of São Paulo, School of Medicine, São Paulo, Brazil.
authors.forename: Haniel
authors.initials: H
authors.lastname: Araujo
authors.affiliation: University of São Paulo, Department of Neurology, Pain Center, São Paulo, Brazil; Instituto do Câncer do Estado de São Paulo, Octavio Frias de Oliveira, Pain Center, São Paulo, Brazil; University of São Paulo, Department and Institute of Psychiatry, Service of Interdisciplinary Neuromodulation (SIN), São Paulo, Brazil.
authors.forename: Sofia Barros
authors.initials: SB
authors.lastname: Cecilio
authors.affiliation: University of São Paulo, Department of Neurology, Pain Center, São Paulo, Brazil; Instituto do Câncer do Estado de São Paulo, Octavio Frias de Oliveira, Pain Center, São Paulo, Brazil.
authors.forename: Irina
authors.initials: I
authors.lastname: Raicher
authors.affiliation: University of São Paulo, Department of Neurology, Pain Center, São Paulo, Brazil; University of São Paulo, Department and Institute of Psychiatry, Service of Interdisciplinary Neuromodulation (SIN), São Paulo, Brazil.
authors.forename: Diego
authors.initials: D
authors.lastname: Toledo
authors.affiliation: University of São Paulo, Department of Neurology, Pain Center, São Paulo, Brazil.
authors.forename: Valquíria
authors.initials: V
authors.lastname: Silva
authors.affiliation: University of São Paulo, School of Medicine, São Paulo, Brazil.
authors.forename: Marco Antonio
authors.initials: MA
authors.lastname: Marcolin
authors.affiliation: University of São Paulo, Department of Neurology, Pain Center, São Paulo, Brazil; Instituto do Câncer do Estado de São Paulo, Octavio Frias de Oliveira, Pain Center, São Paulo, Brazil; University of São Paulo, Department and Institute of Psychiatry, Service of Interdisciplinary Neuromodulation (SIN), São Paulo, Brazil; University of São Paulo, School of Medicine, São Paulo, Brazil.
authors.forename: Manoel Jacobsen
authors.initials: MJ
authors.lastname: Teixeira
authors.affiliation: University of São Paulo, Department of Neurology, Pain Center, São Paulo, Brazil; Instituto do Câncer do Estado de São Paulo, Octavio Frias de Oliveira, Pain Center, São Paulo, Brazil; University of São Paulo, Department and Institute of Psychiatry, Service of Interdisciplinary Neuromodulation (SIN), São Paulo, Brazil. Electronic address: ciampi@usp.br.
authors.forename: Daniel
authors.initials: D
authors.lastname: Ciampi de Andrade
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000071080:Cortical Excitability; D019054:Evoked Potentials, Motor; D005260:Female; D007839:Functional Laterality; D006801:Humans; D008297:Male; D008597:Menstrual Cycle; D008875:Middle Aged; D009044:Motor Cortex / Q000502:physiology*; D015588:Observer Variation; D012737:Sex Factors; D050781:Transcranial Magnetic Stimulation; D055815:Young Adult
keywords: Ageing; Cortex moteur; Cortical excitability; Données normatives; Evoked potentials; Excitabilité corticale; Motor cortex; Neuromodulation; Normative data; Potentiels évoqués; Reference values; Stimulation magnétique transcrânienne; Transcranial magnetic stimulation; Valeurs de référence; Vieillissement