title: Brain responses to visceral stimuli reflect visceral sensitivity thresholds in patients with irritable bowel syndrome.
abstract: OBJECTIVE
  Only a fraction of patients with irritable bowel syndrome (IBS) have increased perceptual sensitivity to rectal distension, indicating differences in processing and/or modulation of visceral afferent signals. We investigated the brain mechanisms of these perceptual differences.
  
  
  METHODS
  We analyzed data from 44 women with IBS and 20 female healthy subjects (controls). IBS symptom severity was determined by a severity scoring system. Anxiety and depression symptoms were assessed using the hospital anxiety and depression score. Blood oxygen level-dependent signals were measured by functional magnetic resonance imaging during expectation and delivery of high (45 mmHg) and low (15 mmHg) intensity rectal distensions. Perception thresholds to rectal distension were determined in the scanner. Brain imaging data were compared among 18 normosensitive and 15 hypersensitive patients with IBS and 18 controls. Results were reported significant if peak P-values were ≤.05, with family-wise error correction in regions of interest.
  
  
  RESULTS
  The subgroups of patients with IBS were similar in age, symptom duration, psychological symptoms, and IBS symptom severity. Although brain responses to distension were similar between normosensitive patients and controls, hypersensitive patients with IBS had greater activation of insula and reduced deactivation in pregenual anterior cingulate cortex during noxious rectal distensions, compared to controls and normosensitive patients with IBS. During expectation of rectal distension, normosensitive patients with IBS had more activation in right hippocampus than controls.
  
  
  CONCLUSIONS
  Despite similarities in symptoms, hyper- and normosensitive patients with IBS differ in cerebral responses to standardized rectal distensions and their expectation, consistent with differences in ascending visceral afferent input.
authors: Department of Clinical and Experimental Medicine/Gastroenterology, Linköping University, Linköping, Sweden.
authors: Mats B O
authors: MB
authors: Larsson
authors: Kirsten
authors: K
authors: Tillisch
authors: A D
authors: AD
authors: Craig
authors: Maria
authors: M
authors: Engström
authors: Jennifer
authors: J
authors: Labus
authors: Bruce
authors: B
authors: Naliboff
authors: Peter
authors: P
authors: Lundberg
authors: Magnus
authors: M
authors: Ström
authors: Emeran A
authors: EA
authors: Mayer
authors: Susanna A
authors: SA
authors: Walter
mesh_terms: D015746:Abdominal Pain / Q000175:diagnosis / Q000503:physiopathology* / Q000523:psychology; D000328:Adult; D000344:Afferent Pathways / Q000503:physiopathology; D001007:Anxiety / Q000503:physiopathology / Q000523:psychology; D001921:Brain / Q000503:physiopathology*; D001931:Brain Mapping / Q000379:methods; D016022:Case-Control Studies; D003863:Depression / Q000503:physiopathology / Q000523:psychology; D005260:Female; D006801:Humans; D043183:Irritable Bowel Syndrome / Q000175:diagnosis / Q000503:physiopathology* / Q000523:psychology; D016014:Linear Models; D008279:Magnetic Resonance Imaging; D040542:Mechanotransduction, Cellular; D008875:Middle Aged; D010147:Pain Measurement; D017288:Pain Threshold; D011312:Pressure; D012007:Rectum / Q000294:innervation*; D011984:Sensory Receptor Cells; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires; D013548:Sweden; D055815:Young Adult