title: Lateralisation of nociceptive processing in the human brain: a functional magnetic resonance imaging study.
abstract: Nociceptive processing within the human brain takes place within two distinct and parallel systems: the lateral and medial pain systems. Current knowledge indicates that the lateral system is involved in processing the sensory-discriminative aspects of pain, and that the medial system is involved in processing the affective-motivational aspects of pain. Hemispheric differences in brain activation (lateralisation) during nociceptive processing were studied to further clarify the division of function between the lateral and medial pain systems. Hemispheric lateralisation was studied by applying painful CO(2) laser stimuli of 3-s duration sequentially to the left and right medial lower calves of five normal right-handed human subjects. The resultant brain activity was measured using 3-T functional magnetic resonance imaging, by determining significant changes in blood oxygen level dependent (BOLD) signal and applying a general linear modelling approach. Volumes of interest were defined for the primary and secondary somatosensory cortices (SI and SII), the insular cortex, and the thalamus, on individual subjects' high-resolution structural scans. Hemispheric lateralisation was quantified by comparing the level of activation between brain hemispheres within each volume of interest. In SII, no significant hemispheric difference in activation was detected. In the insula, activation was significantly greater in the left hemisphere than the right. In both SI and the thalamus, activation in response to painful stimulation was significantly greater in the hemisphere contralateral to the stimulus, which is consistent with these areas being involved in processing the sensory-discriminative aspects of pain.
authors.affiliation: Human Pain Research Group, University of Manchester Rheumatic Diseases Centre, Hope Hospital, Salford M6 8HD, UK.
authors.forename: Paula D
authors.initials: PD
authors.lastname: Youell
authors.forename: Richard G
authors.initials: RG
authors.lastname: Wise
authors.forename: Deborah E
authors.initials: DE
authors.lastname: Bentley
authors.forename: Mark R
authors.initials: MR
authors.lastname: Dickinson
authors.forename: Terence A
authors.initials: TA
authors.lastname: King
authors.forename: Irene
authors.initials: I
authors.lastname: Tracey
authors.forename: Anthony K P
authors.initials: AK
authors.lastname: Jones
mesh_terms: D000328:Adult; D001921:Brain / Q000473:pathology*; D002540:Cerebral Cortex / Q000502:physiology; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006358:Hot Temperature / Q000009:adverse effects; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007834:Lasers; D007866:Leg / Q000294:innervation / Q000502:physiology; D016014:Linear Models; D008279:Magnetic Resonance Imaging; D008297:Male; D009413:Nerve Fibers, Myelinated / Q000502:physiology; D036421:Nerve Fibers, Unmyelinated / Q000502:physiology; D009619:Nociceptors / Q000502:physiology*; D010100:Oxygen / Q000097:blood; D010146:Pain / Q000523:psychology*; D011601:Psychophysics; D013003:Somatosensory Cortex / Q000502:physiology; D013788:Thalamus / Q000502:physiology
chemical_list: D010100:Oxygen