Single-trial detection of human brain responses evoked by laser activation of Adelta-nociceptors using the wavelet transform of EEG epochs.
The aim of this study was to identify EEG changes induced by Adelta-nociceptor activation in single trials. In a preliminary experiment, intense CO(2) laser stimuli were delivered to the hand dorsum of five volunteers. The average amplitude of EEG epochs was estimated in the time-frequency (TF) domain using the continuous Morlet wavelet transform (CMT). The result was used as a TF filter enhancing Adelta-nociceptor induced EEG responses. In a second experiment, eight other subjects were delivered laser stimuli with six intensities. The CMT of each EEG epoch was computed. After applying the TF filter, amplitudes within a predefined interval were summed. Whether this sum predicted the occurrence of Adelta-nociceptor activation was tested using the reaction-time to discriminate between Adelta- or C-fibre mediated detection. Results showed that this method accurately identified single-trial EEG responses to Adelta-nociceptor activation.
Mouraux
André
A
Laboratoire de Neurophysiologie (NEFY), Université Catholique de Louvain, Louvain, Belgium. andre.mouraux@nefy.ucl.ac.be
Plaghki
Léon
L
D000328:Adult; D000344:Afferent Pathways / Q000502:physiology* / Q000528:radiation effects; D002540:Cerebral Cortex / Q000502:physiology*; D004307:Dose-Response Relationship, Radiation; D004569:Electroencephalography / Q000379:methods; D005071:Evoked Potentials / Q000502:physiology*; D005583:Fourier Analysis; D006358:Hot Temperature / Q000009:adverse effects; D006801:Humans; D007834:Lasers; D009413:Nerve Fibers, Myelinated / Q000502:physiology* / Q000528:radiation effects; D036421:Nerve Fibers, Unmyelinated / Q000502:physiology / Q000528:radiation effects; D009619:Nociceptors / Q000502:physiology* / Q000528:radiation effects; D010146:Pain / Q000503:physiopathology*; D011930:Reaction Time / Q000502:physiology / Q000528:radiation effects