Scalp topography of ultralate (C-fibres) evoked potentials following thulium YAG laser stimuli to tiny skin surface areas in humans.
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.
Opsommer
E
E
Faculty of Medicine, Université catholique de Louvain, Avenue Mounier 53/READ 5375, B-1200, Brussels, Belgium. opsommer@read.ucl.ac.be
Weiss
T
T
Miltner
W H
WH
Plaghki
L
L
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*
D013932:Thulium