title: Activation of C-fiber nociceptors by low-power diode laser.
abstract: OBJECTIVE
  The evaluation of selective activation of C-fibers to record evoked potentials using the association of low-power diode laser (810 nm), tiny-area stimulation and skin-blackening.
  
  
  METHODS
  Laser-evoked potentials (LEPs) were obtained from 20 healthy young subjects. An aluminum plate with one thin hole was attached to the laser probe to provide tiny-area stimulation of the hand dorsum and the stimulated area was covered with black ink.
  
  
  RESULTS
  The mean intensity used for eliciting the ultra-late laser-evoked potential (ULEP) was 70 ± 32 mW. All subjects showed a clear biphasic potential that comprised a negative peak (806 ± 61 ms) and a positive deflection (1033 ± 60 ms), corresponding to the ULEP related to C-fiber activation.
  
  
  CONCLUSIONS
  C-fiber-evoked responses can be obtained using a very low-power diode laser when stimulation is applied to tiny areas of darkened skin. This strategy offers a non-invasive and easy methodology that minimizes damage to the tissue.
authors.affiliation: Departamento de Psicobiologia, Universidade Federal de São Paulo, Sao Paulo, SP, Brazil.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Azevedo
authors.affiliation: Departamento de Psicobiologia, Universidade Federal de São Paulo, Sao Paulo, SP, Brazil.
authors.forename: Andressa
authors.initials: A
authors.lastname: Silva
authors.affiliation: Departamento de Psicobiologia, Universidade Federal de São Paulo, Sao Paulo, SP, Brazil.
authors.forename: Raquel
authors.initials: R
authors.lastname: Martins
authors.affiliation: Departamento de Psicobiologia, Universidade Federal de São Paulo, Sao Paulo, SP, Brazil.
authors.forename: Monica L
authors.initials: ML
authors.lastname: Andersen
authors.affiliation: Departamento de Psicobiologia, Universidade Federal de São Paulo, Sao Paulo, SP, Brazil.
authors.forename: Sergio
authors.initials: S
authors.lastname: Tufik
authors.affiliation: Universidade Federal de São Paulo, Sao Paulo, SP, Brazil.
authors.forename: Gilberto M
authors.initials: GM
authors.lastname: Manzano
mesh_terms: D000328:Adult; D005073:Evoked Potentials, Somatosensory / Q000528:radiation effects*; D005260:Female; D006801:Humans; D054023:Lasers, Semiconductor; D008297:Male; D009412:Nerve Fibers / Q000528:radiation effects*; D009619:Nociceptors / Q000528:radiation effects*; D011930:Reaction Time