title: The effect of heterotopic noxious conditioning stimulation on Aδ-, C- and Aβ-fibre brain responses in humans.
abstract: Human studies have shown that heterotopic nociceptive conditioning stimulation (HNCS) applied to a given body location reduces the percept and brain responses elicited by noxious test stimuli delivered at a remote body location. It remains unclear to what extent this effect of HNCS relies on the spinal-bulbar-spinal loop mediating the effect of diffuse noxious inhibitory controls (DNICs) described in animals, and/or on top-down cortical mechanisms modulating nociception. Importantly, some studies have examined the effects of HNCS on the brain responses to nociceptive input conveyed by Aδ-fibres. In contrast, no studies have explored the effects of HNCS on the responses to selective nociceptive C-fibre input and non-nociceptive Aβ-fibre input. In this study, we measured the intensity of perception and event-related potentials (ERPs) to stimuli activating Aδ-, C- and Aβ-fibres, before, during and after HNCS, obtained by immersing one foot in painful cold water. We observed that (i) the perceived intensity of nociceptive Aδ- and C-stimuli was reduced during HNCS, and (ii) the ERPs elicited by Aδ- and Aβ- and C-stimuli were also reduced during HNCS. Importantly, because Aβ-ERPs are related to primary afferents that ascend directly through the dorsal columns without being relayed at spinal level, the modulation of these responses may not be explained by an influence of descending projections modulating the transmission of nociceptive input at spinal level. Therefore, our results indicate that, in humans, HNCS should be used with caution as a direct measure of DNIC-related mechanisms.
authors.affiliation: Laboratoire d'algologie, Institute of Neurosciences (IONS), Université catholique de Louvain, 53, Avenue Mounier - UCL 53.75, B-1200, Bruxelles, Belgium.
authors.forename: Diana M
authors.initials: DM
authors.lastname: Torta
authors.affiliation: Laboratoire d'algologie, Institute of Neurosciences (IONS), Université catholique de Louvain, 53, Avenue Mounier - UCL 53.75, B-1200, Bruxelles, Belgium.|A. Ya. Kozhevnikov Clinic of Nervous Diseases, The I.M. Sechenov First Moscow State Medical University, Moscow, Russia.
authors.forename: Maxim V
authors.initials: MV
authors.lastname: Churyukanov
authors.affiliation: Laboratoire d'algologie, Institute of Neurosciences (IONS), Université catholique de Louvain, 53, Avenue Mounier - UCL 53.75, B-1200, Bruxelles, Belgium.
authors.forename: Leon
authors.initials: L
authors.lastname: Plaghki
authors.affiliation: Laboratoire d'algologie, Institute of Neurosciences (IONS), Université catholique de Louvain, 53, Avenue Mounier - UCL 53.75, B-1200, Bruxelles, Belgium.
authors.forename: André
authors.initials: A
authors.lastname: Mouraux
mesh_terms: D000328:Adult; D002540:Cerebral Cortex / Q000502:physiology*; D003080:Cold Temperature; D004558:Electric Stimulation; D004569:Electroencephalography; D005071:Evoked Potentials; D005260:Female; D006801:Humans; D007834:Lasers; D008297:Male; D008875:Middle Aged; D009413:Nerve Fibers, Myelinated / Q000502:physiology*; D036421:Nerve Fibers, Unmyelinated / Q000502:physiology*; D059225:Nociception / Q000502:physiology*; D010147:Pain Measurement; D017288:Pain Threshold / Q000502:physiology*; D010812:Physical Stimulation; D055815:Young Adult
keywords: cold pressor test; diffuse noxious inhibitory control; event-related potentials; heterotopic noxious conditioning stimuli; pain