title: Scalp topography of ultralate (C-fibres) evoked potentials following thulium YAG laser stimuli to tiny skin surface areas in humans.
abstract: OBJECTIVE
  To investigate (1) the scalp topography of ultralate laser evoked potentials (LEPs) related to C-fibre activation, which can directly be obtained by thulium YAG (Tm YAG) laser stimulation of tiny skin surface areas (about 0.23 mm(2)) and (2) the influence of the performance of a motor task on ultralate LEPs.
  
  
  METHODS
  Laser stimuli were applied to the dorsum of the left hand. LEPs were recorded with 58 scalp electrodes from 9 healthy subjects in two different conditions, with and without a reaction time (RT) task (press a button upon detection).
  
  
  RESULTS
  On high resolution electroenchephalogram recordings, ultralate LEPs were characterized by a broad positive component (peak latency: 1133+/-91 ms) with maximum amplitude about the vertex. Moreover, the performance of a RT task had no influence on latency, amplitude and topographical patterns of two maps chosen at the positive peak latency in ultralate LEPs. Nevertheless, a negative inflexion (latency 1300 ms) appeared after the positive component in the task condition possibly reflecting movement-related potentials.
  
  
  CONCLUSIONS
  Tm YAG laser stimulation of tiny skin surface areas allows recording the dynamic scalp topography of ultralate (C-fibres) LEPs, with or without the performance of a RT task.
authors.affiliation: Faculty of Medicine, Université catholique de Louvain, Avenue Mounier 53/READ 5375, B-1200, Brussels, Belgium. opsommer@read.ucl.ac.be
authors.forename: E
authors.initials: E
authors.lastname: Opsommer
authors.forename: T
authors.initials: T
authors.lastname: Weiss
authors.forename: W H
authors.initials: WH
authors.lastname: Miltner
authors.forename: L
authors.initials: L
authors.lastname: Plaghki
mesh_terms: D000328:Adult; D004569:Electroencephalography; D004585:Electrooculography; D005071:Evoked Potentials / Q000502:physiology*; D005260:Female; D006801:Humans; D007834:Lasers; D008297:Male; D009412:Nerve Fibers / Q000502:physiology*; D010465:Perception / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology; D012867:Skin / Q000294:innervation*; D012879:Skin Physiological Phenomena; D013932:Thulium / Q000494:pharmacology*
chemical_list: D013932:Thulium