Attention-related modifications of ultra-late CO(2) laser evoked potentials to human trigeminal nerve stimulation.
Our study aimed at investigating the scalp topography of ultra-late CO(2) laser evoked potentials (LEPs), which are related to C fiber activation, and at exploring the effect of attention deviation on ultra-late LEPs. Brain responses to non-painful CO(2) laser stimuli were recorded in ten healthy subjects in three different conditions: (i) neutral condition in which subjects did not have any task; (ii) distraction condition in which subjects were asked to perform a mathematical task; and (iii) attention condition in which subjects had to count the number of stimuli. In all subjects, also A fiber-related late LEPs were recorded after painful CO(2) laser stimulation. The ultra-late LEPs in attention condition included an earlier negative potential (ultra-late N1) in the contralateral temporal region and a simultaneous frontal positive response (ultra-late P1). Later, a vertex biphasic component (ultra-late N2a and ultra-late P2) was identifiable. The vertex ultra-late LEP amplitude was significantly decreased in both neutral and distraction condition. Ultra-late LEPs showed a longer latency than late LEPs, but the scalp distributions of both ultra-late and late LEPs were very similar, thus suggesting that the same cerebral areas may be involved in their generation. Since attention deviations have a strong effect on ultra-late LEP amplitude, the subject's attention should be addressed to CO(2) laser stimuli when ultra-late LEPs are used for clinical purposes.
Department of Neurology, Università Cattolica del Sacro Cuore, L.go A. Gemelli 8, 00168 Rome, Italy. m.valeriani@tiscalinet.it
Massimiliano
M
Valeriani
Domenico
D
Restuccia
Domenica
D
Le Pera
Liala
L
De Armas
Toni
T
Maiese
Pietro
P
Tonali
D000328:Adult; D001288:Attention / Q000502:physiology*; D002245:Carbon Dioxide; D005073:Evoked Potentials, Somatosensory / Q000502:physiology*; D005260:Female; D006801:Humans; D007834:Lasers; D008297:Male; D009412:Nerve Fibers / Q000502:physiology; D009413:Nerve Fibers, Myelinated / Q000502:physiology; D010146:Pain / Q000503:physiopathology; D011930:Reaction Time / Q000502:physiology; D014276:Trigeminal Nerve / Q000166:cytology / Q000502:physiology*
D002245:Carbon Dioxide