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- Title
Somatotopic Representation of Second Pain in the Primary Somatosensory Cortex of Humans and Rodents.
- Authors
Jin, Q. Q.; Wu, G. Q.; Xia, X. L.; Hu, L.; Peng, W. W.; Iannetti, G. D.
- Abstract
There is now compelling evidence that selective stimulation of AS nociceptors eliciting first pain evokes robust responses in the primary somatosensory cortex (SI). In contrast, whether the C-fiber nociceptive input eliciting second pain has an organized projection to SI remains an open question. Here, we recorded the electrocortical responses elicited by nociceptive-specific laser stimulation of the four limbs in 202 humans (both males and females, using EEG) and 12 freely moving rats (all males, using ECoG). Topographical analysis and source modeling revealed in both species, a clear gross somatotopy of the unmyelinated C-fiber input within the S1 contralateral to the stimulated side. In the human EEG, SI activity could be isolated as an early-latency negative deflection (C-Nl wave peaking at 710-730 ms) after hand stimulation, but not after foot stimulation because of the spatiotemporal overlap with the subsequent large-amplitude supramodal vertex waves (C-N2/P2). In contrast, because of the across-species difference in the representation of the body surface within SI, SI activity could be isolated in rat ECoG as a C-Nl after both forepaw and hindpaw stimulation. Finally, we observed a functional dissociation between the generators ot the somatosensory-specific lateralized waves (C-Nl) and those of the supramodal vertex waves (C-N2/P2), indicating that C-fiber unmyelinated input is processed in functionally distinct somatosensory and multimodal cortical areas. These findings demonstrated that C-fiber input conveys information about the spatial location of noxious stimulation across the body surface, a prerequisite for deploying an appropriate defensive motor repertoire.
- Subjects
SOMATOSENSORY cortex; PAIN; NERVE fibers; ELECTROENCEPHALOGRAPHY; LABORATORY rats; BRAIN function localization
- Publication
Journal of Neuroscience, 2018, Vol 38, Issue 24, p5538
- ISSN
0270-6474
- Publication type
Article
- DOI
10.1523/JNEUROSCI.3654-17.2018