title: Mapping brain response to pain in fibromyalgia patients using temporal analysis of FMRI.
abstract: BACKGROUND
  Nociceptive stimuli may evoke brain responses longer than the stimulus duration often partially detected by conventional neuroimaging. Fibromyalgia patients typically complain of severe pain from gentle stimuli. We aimed to characterize brain response to painful pressure in fibromyalgia patients by generating activation maps adjusted for the duration of brain responses.
  
  
  RESULTS
  Twenty-seven women (mean age: 47.8 years) were assessed with fMRI. The sample included nine fibromyalgia patients and nine healthy subjects who received 4 kg/cm(2) of pressure on the thumb. Nine additional control subjects received 6.8 kg/cm(2) to match the patients for the severity of perceived pain. Independent Component Analysis characterized the temporal dynamics of the actual brain response to pressure. Statistical parametric maps were estimated using the obtained time courses. Brain response to pressure (18 seconds) consistently exceeded the stimulus application (9 seconds) in somatosensory regions in all groups. fMRI maps following such temporal dynamics showed a complete pain network response (sensory-motor cortices, operculo-insula, cingulate cortex, and basal ganglia) to 4 kg/cm(2) of pressure in fibromyalgia patients. In healthy subjects, response to this low intensity pressure involved mainly somatosensory cortices. When matched for perceived pain (6.8 kg/cm(2)), control subjects showed also comprehensive activation of pain-related regions, but fibromyalgia patients showed significantly larger activation in the anterior insula-basal ganglia complex and the cingulate cortex.
  
  
  CONCLUSIONS
  The results suggest that data-driven fMRI assessments may complement conventional neuroimaging for characterizing pain responses and that enhancement of brain activation in fibromyalgia patients may be particularly relevant in emotion-related regions.
authors.affiliation: Institut d'Alta Tecnologia-PRBB, CRC Corporació Sanitària, Barcelona, Spain. jpujol@crccorp.es
authors.forename: Jesus
authors.initials: J
authors.lastname: Pujol
authors.forename: Marina
authors.initials: M
authors.lastname: López-Solà
authors.forename: Héctor
authors.initials: H
authors.lastname: Ortiz
authors.forename: Joan Carles
authors.initials: JC
authors.lastname: Vilanova
authors.forename: Ben J
authors.initials: BJ
authors.lastname: Harrison
authors.forename: Murat
authors.initials: M
authors.lastname: Yücel
authors.forename: Carles
authors.initials: C
authors.lastname: Soriano-Mas
authors.forename: Narcís
authors.initials: N
authors.lastname: Cardoner
authors.forename: Joan
authors.initials: J
authors.lastname: Deus
mesh_terms: D001921:Brain / Q000503:physiopathology*; D016022:Case-Control Studies; D005260:Female; D005356:Fibromyalgia / Q000503:physiopathology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008875:Middle Aged; D010146:Pain / Q000503:physiopathology*