title: Sex differences in the neural representation of pain unpleasantness.
abstract: Sex differences in pain perception are still poorly understood, but they may be related to the way the brains of men and women respond to the affective dimensions of pain. Using a matched pain intensity paradigm, where pain intensity was kept constant across participants but pain unpleasantness was left free to vary among participants, we studied the relationship between pain unpleasantness and pain-evoked brain activity in healthy men and women separately. Experimental pain was provoked using transcutaneous electrical stimulation of the sural nerve while pain-related brain activity was measured using somatosensory-evoked brain potentials with source localization. Cardiac responses to pain were also measured using electrocardiac recordings. Results revealed that subjective pain unpleasantness was strongly associated with increased perigenual anterior cingulate cortex activity in women, whereas it was strongly associated with decreased ventromedial prefrontal cortex activity in men. Only ventromedial prefrontal cortex deactivations in men were additionally associated with increased autonomic cardiac arousal. These results suggest that in order to deal with pain's objectionable properties, men preferentially deactivate prefrontal suppression regions, leading to the mobilization of threat-control circuits, whereas women recruit well-known emotion-processing areas of the brain.
  
  
  CONCLUSIONS
  This article presents neuroimaging findings demonstrating that subjective pain unpleasantness ratings are associated with different pain-evoked brain responses in men and women, which has potentially important implications regarding sex differences in the risk of developing chronic pain.
authors.affiliation: School of Rehabilitation, Faculty of Medicine and Health Science, Université de Sherbrooke, Sherbrooke, Quebec, Canada.
authors.forename: Lydia
authors.initials: L
authors.lastname: Girard-Tremblay
authors.affiliation: School of Rehabilitation, Faculty of Medicine and Health Science, Université de Sherbrooke, Sherbrooke, Quebec, Canada.
authors.forename: Vincent
authors.initials: V
authors.lastname: Auclair
authors.affiliation: School of Rehabilitation, Faculty of Medicine and Health Science, Université de Sherbrooke, Sherbrooke, Quebec, Canada.
authors.forename: Kathya
authors.initials: K
authors.lastname: Daigle
authors.affiliation: School of Rehabilitation, Faculty of Medicine and Health Science, Université de Sherbrooke, Sherbrooke, Quebec, Canada.
authors.forename: Guillaume
authors.initials: G
authors.lastname: Léonard
authors.affiliation: Department of Diagnostic Radiology, Faculty of Medicine and Health Science, Université de Sherbrooke, Sherbrooke, Quebec, Canada; Sherbrooke Molecular Imaging Center, Department of Nuclear Medicine and Radiobiology, Faculty of Medicine and Health Science, Université de Sherbrooke, Sherbrooke, Quebec, Canada.
authors.forename: Kevin
authors.initials: K
authors.lastname: Whittingstall
authors.affiliation: School of Rehabilitation, Faculty of Medicine and Health Science, Université de Sherbrooke, Sherbrooke, Quebec, Canada. Electronic address: Philippe.Goffaux@USherbrooke.ca.
authors.forename: Philippe
authors.initials: P
authors.lastname: Goffaux
mesh_terms: D000328:Adult; D001703:Biophysics; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000502:physiology; D004558:Electric Stimulation / Q000009:adverse effects; D004569:Electroencephalography; D005073:Evoked Potentials, Somatosensory / Q000502:physiology; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D059906:Neuroimaging; D010146:Pain / Q000523:psychology*; D010147:Pain Measurement; D058748:Pain Perception / Q000502:physiology*; D012737:Sex Factors; D013497:Sural Nerve / Q000502:physiology; D055815:Young Adult
keywords: Sex differences; brain; pain unpleasantness; somatosensory-evoked brain potential; source localization