title: Deficient habituation to repeated rectal distensions in irritable bowel syndrome patients with visceral hypersensitivity.
abstract: BACKGROUND
  Irritable bowel syndrome (IBS) patients show evidence of altered central processing of visceral signals. One of the proposed alterations in sensory processing is an altered engagement of endogenous pain modulation mechanisms. The aim was to test the hypothesis that IBS patients with (IBS-S) and without visceral hypersensitivity (IBS-N) differ in their ability to engage endogenous pain modulation mechanism during habituation to repeated visceral stimuli.
  
  
  METHODS
  Brain blood oxygen level dependent (BOLD) response was measured during repeated rectal distension and its anticipation in 33 IBS patients with and without visceral hypersensitivity and 18 healthy controls (HCs). BOLD response to early and late phase of the distension series was compared within and between groups.
  
  
  RESULTS
  While BOLD response was similar during the early phase of the experiment, IBS-S showed greater BOLD response than IBS-N and HCs during the late phase of the distension series. IBS-S showed increasing BOLD response both to the anticipation and delivery of low intensity rectal distensions in brain regions including insula, anterior and mid cingulate cortex. IBS-N showed decreasing BOLD response to repeated rectal distensions in brain regions including insula, prefrontal cortex and amygdala.
  
  
  CONCLUSIONS
  These findings are consistent with compromised ability of IBS-S to respond to repeated delivery of rectal stimuli, both in terms of sensitization of sensory pathways and habituation of emotional arousal. The fact that both IBS subgroups met Rome criteria, and did not differ in terms of reported symptom severity demonstrates that similar symptom patterns can result from different underlying neurobiological mechanisms.
authors.affiliation: Department of Gastroenterology and Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden; Center for Medical Image Science and Visualization (CMIV), Linköping University, Linköping, Sweden.
authors.forename: M B O
authors.initials: MB
authors.lastname: Lowén
authors.forename: E
authors.initials: E
authors.lastname: Mayer
authors.forename: K
authors.initials: K
authors.lastname: Tillisch
authors.forename: J
authors.initials: J
authors.lastname: Labus
authors.forename: B
authors.initials: B
authors.lastname: Naliboff
authors.forename: P
authors.initials: P
authors.lastname: Lundberg
authors.forename: L-H
authors.initials: LH
authors.lastname: Thorell
authors.forename: M
authors.initials: M
authors.lastname: Ström
authors.forename: M
authors.initials: M
authors.lastname: Engström
authors.forename: S
authors.initials: S
authors.lastname: Walter
mesh_terms: D000328:Adult; D059031:Anticipation, Psychological; D001007:Anxiety / Q000523:psychology; D001921:Brain / Q000503:physiopathology*; D016022:Case-Control Studies; D003863:Depression / Q000523:psychology; D004106:Dilatation; D005260:Female; D059907:Functional Neuroimaging; D006185:Habituation, Psychophysiologic / Q000502:physiology*; D006801:Humans; D043183:Irritable Bowel Syndrome / Q000150:complications / Q000503:physiopathology* / Q000523:psychology; D008279:Magnetic Resonance Imaging; D008875:Middle Aged; D011312:Pressure; D012007:Rectum; D020886:Somatosensory Disorders / Q000150:complications / Q000503:physiopathology* / Q000523:psychology; D059265:Visceral Pain / Q000150:complications / Q000503:physiopathology* / Q000523:psychology; D055815:Young Adult
keywords: brain-gut interaction; fMRI; irritable bowel syndrome; visceral sensitivity