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Cortical inhibition of laser pain and laser‐evoked potentials by non‐nociceptive somatosensory input
Author(s) -
Testani Elisa,
Le Pera Domenica,
Del Percio Claudio,
Miliucci Roberto,
Brancucci Alfredo,
Pazzaglia Costanza,
De Armas Liala,
Babiloni Claudio,
Rossini Paolo Maria,
Valeriani Massimiliano
Publication year - 2015
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1111/ejn.13035
Subject(s) - nociception , somatosensory system , stimulation , neuroscience , scalp , evoked potential , somatosensory evoked potential , psychology , summation , spinal cord , medicine , anesthesia , anatomy , receptor
Abstract Although the inhibitory action that tactile stimuli can have on pain is well documented, the precise timing of the interaction between the painful and non‐painful stimuli in the central nervous system is unclear. The aim of this study was to investigate this issue by measuring the timing of the amplitude modulation of laser evoked potentials ( LEP s) due to conditioning non‐painful stimuli. LEP s were recorded from 31 scalp electrodes in 10 healthy subjects after painful stimulation of the right arm (C6–C7 dermatomes). Non‐painful electrical stimuli were applied by ring electrodes on the second and third finger of the right hand. Electrical stimuli were delivered at +50, +150, +200 and +250 ms interstimulus intervals ( ISI s) after the laser pulses. LEP s obtained without any conditioning stimulation were used as a baseline. As compared to the baseline, non‐painful electrical stimulation reduced the amplitude of the vertex N2/P2 LEP component and the laser pain rating when electrical stimuli followed the laser pulses only at +150 and +200 ms ISI s. As at these ISI s the collision between the non‐painful and painful input is likely to take place at the cortical level, we can conclude that the late processing of painful (thermal) stimuli is partially inhibited by the processing of non‐painful (cutaneous) stimuli within the cerebral cortex. Moreover, our results do not provide evidence that non‐painful inputs can inhibit pain at a lower level, including the spinal cord.