Novel Evidence for Hypersensitivity of Visceral Sensory Neural Circuitry in Irritable Bowel Syndrome Patients  Adeyemi Lawal, Mark Kern, Harjot Sidhu, Candy Hofmann, Reza Shaker  Gastroenterology  Volume 130, Issue 1, Pages 26-33 (January 2006) DOI: 10.1053/j.gastro.2005.10.020 Copyright © 2006 American Gastroenterological Association Terms and Conditions

Figure 1 The presence or absence of cortical fMRI activity to all tested rectal pressures. Presence of fMRI activity is shown by a + symbol and its absence is shown by a − symbol. In addition to the perceived distention (shown in red), several unperceived distentions also induced cortical activity. Three levels of subliminal rectal distention pressure, 10, 15, and 20 mm Hg, were represented in the subliminal domain of the healthy controls and IBS patients tested in the present study. Gastroenterology 2006 130, 26-33DOI: (10.1053/j.gastro.2005.10.020) Copyright © 2006 American Gastroenterological Association Terms and Conditions

Figure 2 Total fMRI cortical activity volume response to 3 levels of subliminal rectal distention pressures in IBS patients and controls. In all 3 subliminal distention pressures the fMRI activity volumes in IBS patients were significantly larger than those of controls. Furthermore, fMRI cortical activity volumes showed a stimulus intensity–dependent relationship in controls (P < .001), but not in IBS patients for the 3 analyzed pressure levels. Gastroenterology 2006 130, 26-33DOI: (10.1053/j.gastro.2005.10.020) Copyright © 2006 American Gastroenterological Association Terms and Conditions

Figure 3 fMRI impulse response waveforms (signal intensity) induced by the 3 levels of subliminal distention pressures in IBS patients and controls. There was a progressive increase in maximum fMRI signal strength that was related directly to stimulus intensity in both groups. However, the stimulus intensity–related fMRI signal changes were similar between the 2 groups. Gastroenterology 2006 130, 26-33DOI: (10.1053/j.gastro.2005.10.020) Copyright © 2006 American Gastroenterological Association Terms and Conditions

Figure 4 The anatomic location of composite fMRI activity associated with subliminal rectal distention in 10 diarrhea-predominant female IBS patients. FMRI activity can be characterized to exist in 5 broad cortical regions: the sensory/motor, the parietal/occipital, the cingulate gyrus, the prefrontal cortex, and the insula cortex. Gastroenterology 2006 130, 26-33DOI: (10.1053/j.gastro.2005.10.020) Copyright © 2006 American Gastroenterological Association Terms and Conditions

Figure 5 Comparison of the perception thresholds determined by the ascending method of limits and forced choice technique using 3-foot and 30-foot long barostat connecting catheters in 5 healthy volunteers. For both techniques the use of a longer connecting tube resulted in a significantly higher distention pressure for perception threshold (P < .05). The perception threshold using the ascending method of limits and forced choice technique were similar irrespective of the length of the connecting tube. *P < .05. Gastroenterology 2006 130, 26-33DOI: (10.1053/j.gastro.2005.10.020) Copyright © 2006 American Gastroenterological Association Terms and Conditions