|Reference code: ||PT/FB/BL-2010-215.07|
|Location: ||Arquivo PCA - Pasta 7/2010|
|Modulation of cortical responses to nociceptive stimuli by vestibular stimulation. A laser-evoked potentials study|
|Publication year: ||2012|
The vestibular system is unique among the senses because of the entirely multisensory nature of its cortical projections. Neuroanatomical and neuroimaging studies show that vestibular stimulation activates somatosensory areas, and particularly the so-called parieto-insular vestibular cortex (PIVC) in the monkey, while deactivating visual areas. This arrangement suggests that vestibular input could influence sensory processing in other sensory modalities. Human clinical studies reported dramatic perceptual changes following caloric vestibular stimulation (CVS), including transient remission of tactile imperception and chronic pain in brain-damaged patients. We recently observed in healthy participants that CVS decreases perceptual thresholds for touch, but increases thresholds for pain. These results suggested a direct role of vestibular inputs in multisensory interactions with touch and pain. Although an enhancement in the somatosensory evoked potentials (N80) has been demonstrated, the neural mechanisms underlying vestibular-induced analgesia remain unclear.
To address this issue we delivered nociceptive laser stimuli to the left hand dorsum before (‘Baseline’ condition) and immediately after left cold CVS (‘CVS’ condition), and recorded the corresponding brain responses (laser-evoked potentials, LEPs) together with the single-trial ratings of subjective pain intensity. To control for non-specific effects (e.g. time-dependent habituation) both LEPs and intensity ratings were also recorded one hour after CVS (‘Post’ condition).
A significant analgesic effect was induced by left CVS, as reported in lower pain ratings in ‘CVS’ compared to both ‘Baseline’ and ‘Post’ (p=0.016 and p=0.001, respectively). No differences in pain ratings were found between ‘Baseline’ and ‘Post’. Left CVS reduced the amplitude of standard LEP peaks, relative to ‘Pre’ and ‘Post’, both in the early time-window of the N1 wave (all p<0.01) and in the later time-windows of the N2 (all p<0.005) and P2 waves (all p<0.05). There were trends for habituation of the N2 and P2 peaks between 'Pre' and 'Post' conditions (p=0.06 and p=0.10, respectively).
These results provide the first evidence that left CVS reduces the cortical responses to nociceptive laser stimulation, including components localised to the primary somatosensory cortex. Thus, the vestibular system directly modulates activity in somatosensory pathways. This analgesic effect induced by left CVS could involve either subcortical gating of the nociceptive input, or by a direct modulation of evoked somatosensory cortex activity, by concurrent vestibular inputs to the same area.
|Accessibility: ||Document does not exist in file|
|Ferrè, E. R.|
|Secondary author(s): |
|Haggard, P., Bottini, G., Iannetti, G. D. |
|Document type: |
|Number of reproductions: |
|Ferrè, E. R., Haggard, P., Bottini, G., & Iannetti, G. D. (2012). Modulation of cortical responses to nociceptive stimuli by vestibular stimulation. A laser-evoked potentials study. Program No. 828.09. Neuroscience Meeting Planner. New Orleans, LA: Society for Neuroscience, 2012. Online.|
|Indexed document: ||No|
|Keywords: ||Vestibular / Pain / Multisensory|