title: Role of primary somatosensory cortex in the coding of pain.
abstract: The intensity and submodality of pain are widely attributed to stimulus encoding by peripheral and subcortical spinal/trigeminal portions of the somatosensory nervous system. Consistent with this interpretation are studies of surgically anesthetized animals, demonstrating that relationships between nociceptive stimulation and activation of neurons are similar at subcortical levels of somatosensory projection and within the primary somatosensory cortex (in cytoarchitectural areas 3b and 1 of somatosensory cortex, SI). Such findings have led to characterizations of SI as a network that preserves, rather than transforms, the excitatory drive it receives from subcortical levels. Inconsistent with this perspective are images and neurophysiological recordings of SI neurons in lightly anesthetized primates. These studies demonstrate that an extreme anterior position within SI (area 3a) receives input originating predominantly from unmyelinated nociceptors, distinguishing it from posterior SI (areas 3b and 1), long recognized as receiving input predominantly from myelinated afferents, including nociceptors. Of particular importance, interactions between these subregions during maintained nociceptive stimulation are accompanied by an altered SI response to myelinated and unmyelinated nociceptors. A revised view of pain coding within SI cortex is discussed, and potentially significant clinical implications are emphasized.
authors.affiliation: Department of Neuroscience, University of Florida College of Medicine, Gainesville, FL 32610-0244, USA Department of Physiology, University of North Carolina School of Medicine, Chapel Hill, NC, USA Department of Computer Sciences, University of North Carolina School of Medicine, Chapel Hill, NC, USA Senior School, Shadyside Academy, Pittsburgh, PA, USA.
authors.forename: Charles J
authors.initials: CJ
authors.lastname: Vierck
authors.forename: Barry L
authors.initials: BL
authors.lastname: Whitsel
authors.forename: Oleg V
authors.initials: OV
authors.lastname: Favorov
authors.forename: Alexander W
authors.initials: AW
authors.lastname: Brown
authors.forename: Mark
authors.initials: M
authors.lastname: Tommerdahl
mesh_terms: D000344:Afferent Pathways / Q000502:physiology; D000758:Anesthesia; D000818:Animals; D001370:Axonal Transport; D006801:Humans; D008959:Models, Neurological; D009413:Nerve Fibers, Myelinated / Q000502:physiology; D036421:Nerve Fibers, Unmyelinated / Q000502:physiology; D009619:Nociceptors / Q000502:physiology*; D058748:Pain Perception / Q000502:physiology*; D017288:Pain Threshold / Q000502:physiology; D020671:Posterior Horn Cells / Q000502:physiology; D012453:Saimiri; D012867:Skin / Q000294:innervation; D013003:Somatosensory Cortex / Q000503:physiopathology*; D013133:Spinothalamic Tracts / Q000503:physiopathology; D013787:Thalamic Nuclei / Q000503:physiopathology; D014110:Touch / Q000502:physiology; D014851:Wakefulness