title: Excitability of the Adelta nociceptive pathways as assessed by the recovery cycle of laser evoked potentials in humans.
abstract: To investigate the excitability of Adelta nociceptive pathways and the nature of the vertex laser evoked potentials (LEPs), we studied the recovery cycle of the P2-LEP component and compared it with that of the P200 of the somatosensory evoked potential (SEP). Using two identical CO(2)-laser stimulators, we delivered paired stimuli to two adjacent skin spots on the hand at interstimulus intervals ranging from 250 ms to 2 s. The test P2-LEP was strongly inhibited at the 250-ms interstimulus interval ( P<0.01) and progressively recovered by the 2-s interval. The P200-SEP, after paired stimuli to the median nerve, showed a time course even slower than the P2-LEP ( P<0.01). Besides providing the LEP recovery curve in normal subjects, our findings indicate that the P2-LEP relays through a number of synapses similar to (or even lower than) that for the P200-SEP, thus lending further support to the view that the nociceptive P2-LEP is not an endogenous potential equivalent to the P300.
authors.affiliation: Department of Neurological Sciences, University "La Sapienza", Viale Università 30, 00185, Rome, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Truini
authors.forename: P
authors.initials: P
authors.lastname: Rossi
authors.forename: F
authors.initials: F
authors.lastname: Galeotti
authors.forename: A
authors.initials: A
authors.lastname: Romaniello
authors.forename: M
authors.initials: M
authors.lastname: Virtuoso
authors.forename: C
authors.initials: C
authors.lastname: De Lena
authors.forename: M
authors.initials: M
authors.lastname: Leandri
authors.forename: G
authors.initials: G
authors.lastname: Cruccu
mesh_terms: D000328:Adult; D004558:Electric Stimulation / Q000379:methods; D005073:Evoked Potentials, Somatosensory / Q000502:physiology*; D006358:Hot Temperature; D006801:Humans; D007834:Lasers; D009412:Nerve Fibers / Q000502:physiology*; D009434:Neural Pathways / Q000502:physiology; D009619:Nociceptors / Q000502:physiology*; D010147:Pain Measurement / Q000379:methods; D017288:Pain Threshold / Q000502:physiology; D020127:Recovery of Function / Q000502:physiology*