Caloric vestibular stimulation modulates nociceptive evoked potentials.
Vestibular stimulation has been reported to alleviate central pain. Clinical and physiological studies confirm pervasive interactions between vestibular signals and somatosensory circuits, including nociception. However, the neural mechanisms underlying vestibular-induced analgesia remain unclear, and previous clinical studies cannot rule out explanations based on alternative, non-specific effects such as distraction or placebo. To investigate how vestibular inputs influence nociception, we combined caloric vestibular stimulation (CVS) with psychophysical and electrocortical responses elicited by nociceptive-specific laser stimulation in humans (laser-evoked potentials, LEPs). Cold water CVS applied to the left ear resulted in significantly lower subjective pain intensity for experimental laser pain to the left hand immediately after CVS, relative both to before CVS and to 1 h after CVS. This transient reduction in pain perception was associated with reduced amplitude of all LEP components, including the early N1 wave reflecting the first arrival of nociceptive input to primary somatosensory cortex. We conclude that cold left ear CVS elicits a modulation of both nociceptive processing and pain perception. The analgesic effect induced by CVS could be mediated either by subcortical gating of the ascending nociceptive input, or by direct modulation of the primary somatosensory cortex.
Institute of Cognitive Neuroscience, University College London, London, UK. e.ferre@ucl.ac.uk.
Elisa Raffaella
ER
Ferrè
Institute of Cognitive Neuroscience, University College London, London, UK.
Patrick
P
Haggard
Department of Brain and Behavioural Sciences, University of Pavia, Pavia, Italy.|Cognitive Neuropsychology Laboratory, Niguarda Ca' Granda Hospital, Milan, Italy.
Gabriella
G
Bottini
Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK.
Gian Domenico
GD
Iannetti
D000328:Adult; D000698:Analgesia / Q000379:methods*; D002150:Caloric Tests; D002540:Cerebral Cortex / Q000502:physiology*; D005260:Female; D006801:Humans; D066331:Laser-Evoked Potentials / Q000502:physiology*; D008297:Male; D059225:Nociception / Q000502:physiology*; D014722:Vestibule, Labyrinth / Q000502:physiology*; D055815:Young Adult
Analgesia; Caloric vestibular stimulation; Laser-evoked potentials; Multisensory modulation; Nociception; Vestibular system