title: On the selective activation of unmyelinated C-fibers using sinusoidal electrical stimulation: an ERP study.
abstract: OBJECTIVE
  To verify the possibility of selective activation of C-fibers by a 5-Hz transcutaneous electrical stimulus.
  
  
  METHODS
  Because Aβ-, Aδ- and C-fibers have different conduction velocities, we verified the selective activation of A- and C-fibers on the basis of evoked potential latencies. We tested whether a 5-Hz sinusoidal electric stimulus could selectively activate C-fibers and consequently generate ultra-late N2/P2 components in the 750-1200 ms range.
  
  
  RESULTS
  We found that a 5-Hz sine wave stimulus, whether of high or low intensity, elicited N2/P2 complexes only in the late latencies (160-390 ms), suggesting that A-fibers were concomitantly activated along with C-fibers.
  
  
  CONCLUSIONS
  These findings are in agreement with those of previous simulation studies suggesting that activation of fibers of diameter less than 2.5 μm (i.e., C-fibers) at the 5-Hz frequency requires accompanying activity from Aβ- and Aδ-fibers.
  
  
  CONCLUSIONS
  Transcutaneous electrical stimulation with sine wave currents of different frequencies does not seem to be a reliable method for the selective assessment of somatosensory pathways.
authors.affiliation: Laboratoire d'Imagerie & Neurosciences Cognitives, UMR 7237, Université de Strasbourg-CNRS, 21 rue Becquerel-67087, France. andre.dufour@unistra.fr
authors.forename: André
authors.initials: A
authors.lastname: Dufour
authors.forename: Slava
authors.initials: S
authors.lastname: Guergova
authors.forename: Thierry
authors.initials: T
authors.lastname: Pebayle
authors.forename: Pascale
authors.initials: P
authors.lastname: Touzalin-Chretien
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000328:Adult; D005071:Evoked Potentials / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D036421:Nerve Fibers, Unmyelinated / Q000502:physiology*; D009431:Neural Conduction / Q000502:physiology*; D004561:Transcutaneous Electric Nerve Stimulation / Q000379:methods*