Liang, M;
Lee, MC;
O'Neill, J;
Dickenson, AH;
Iannetti, GD;
(2016)
Brain potentials evoked by intraepidermal electrical stimuli reflect the central sensitization of nociceptive pathways.
Journal of Neurophysiology
, 116
(2)
pp. 286-295.
10.1152/jn.00013.2016.
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Abstract
Central sensitization (CS), the increased sensitivity of the central nervous system to somatosensory inputs, accounts for secondary hyperalgesia, a typical sign of several painful clinical conditions. Brain potentials elicited by mechanical punctate stimulation using flat-tip probes can provide neural correlates of CS, but their signal-to-noise ratio is limited by poor synchronisation of the afferent nociceptive input. Additionally, mechanical punctate stimulation does not activate nociceptors exclusively. In contrast, low-intensity intra-epidermal electrical stimulation (IES) allows selective activation of type-II Aδ mechano-heat nociceptors (II-AMHs), and elicits reproducible brain potentials. However, it is unclear whether hyperalgesia from IES occurs and co-exists with secondary mechanical punctate hyperalgesia, and whether the magnitude of the EEG responses evoked by IES within the hyperalgesic area is increased. To address these questions, we explored the modulation of the psychophysical and EEG responses to IES by intra-epidermal injection of capsaicin in healthy human subjects. We obtained three main results. First, the intensity of the sensation elicited by IES was significantly increased in participants who developed robust mechanical punctate hyperalgesia after capsaicin injection (i.e., responders), indicating that hyperalgesia from IES co-exists with punctate mechanical hyperalgesia. Second, the N2 peak magnitude of the EEG responses elicited by IES were significantly increased after the intra-epidermal injection of capsaicin in responders only. Third, a receiver-operator characteristics analysis showed that the N2 peak amplitude is clearly predictive of the presence of CS. These findings suggest that the EEG responses elicited by IES reflect secondary hyperalgesia, and therefore represent an objective correlate of CS.
Type: | Article |
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Title: | Brain potentials evoked by intraepidermal electrical stimuli reflect the central sensitization of nociceptive pathways |
Open access status: | An open access version is available from UCL Discovery |
DOI: | 10.1152/jn.00013.2016 |
Publisher version: | http://dx.doi.org/10.1152/jn.00013.2016 |
Language: | English |
Additional information: | Copyright © 2016 by the American Physiological Society. Licensed under Creative Commons Attribution CC-BY 3.0: the American Physiological Society. |
Keywords: | EEG, central sensitization, intraepidermal electrical stimulation, mechanical punctate stimulation, secondary hyperalgesia |
UCL classification: | UCL UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences > Div of Biosciences UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences > Div of Biosciences > Neuro, Physiology and Pharmacology |
URI: | https://discovery.ucl.ac.uk/id/eprint/1495805 |
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