Effects of attention, distraction and sleep on CO(2) laser evoked potentials related to C-fibers in humans.
OBJECTIVE
The objective of this study is to evaluate the effects of attention, distraction and sleep on CO(2) laser-evoked potentials (LEP) relating to C-fibers (ultra-late LEP).


METHODS
Non-painful CO(2) laser pulses were delivered to a tiny skin area of the dorsum of the right hand. Ultra-late LEP were recorded from 10 normal subjects in 5 different conditions: control (wakefulness), attention, distraction, drowsiness and sleep (stage 2).


RESULTS
The amplitude of ultra-late LEP was slightly increased during attention and significantly decreased during distraction, relative to the control. The ultra-late LEP decreased much in amplitude or almost disappeared during sleep. However, significant differences in latency among the conditions were not found.


CONCLUSIONS
We confirmed that the brain responses relating to signals ascending through C-fibers were much affected by the level of consciousness, being consistent with the findings of late LEP relating to Adelta-fibers. This is the first study to indicate the important characteristics of ultra-late LEP relating to consciousness, suggesting that they include cognitive function and also that one has to be careful of the change in alertness when recording.
D000328:Adult; D001143:Arousal / Q000502:physiology*; D001288:Attention / Q000502:physiology*; D001827:Body Height; D001835:Body Weight; D002245:Carbon Dioxide; D005071:Evoked Potentials / Q000528:radiation effects*; D005260:Female; D006801:Humans; D007834:Lasers; D008297:Male; D008875:Middle Aged; D011930:Reaction Time; D012890:Sleep / Q000528:radiation effects*
D002245:Carbon Dioxide