We analyzed brain activity during infusion of acid or isotonic saline into the esophagus using group independent component selleck screening library analysis (ICA),4 a general method that does not depend on a priori information of the task. Six healthy male

volunteers (29–45 years old) were studied. All the volunteers gave us written informed consent for participation of the study, and the study protocol was approved by the Internal Review Board of Juntendo University Hospital. A multi-lumen catheter was inserted transnasally and side-hole infusions ports were approximately 15 cm proximal to the lower esophageal sphincter. The experimental protocol was a 5-min interval, 5-min isotonic saline infusion, 5-min interval, 5-min 0.1 N HCl infusion and a final 5-min interval. The infusion rate for both saline and HCl was 2 mL/min. Subjects were left uninformed of the experimental protocol, and did not know when and what kind of liquid was infused into the esophagus. When the subjects perceive heartburn,

they immediately push a button-response device, and then push the button twice soon after the cessation of a heartburn episode. They were also questioned selleck kinase inhibitor about the feeling during magnetic resonance (MR) scanning after the end of the examination. Magnetic resonance images were acquired on a Philips 3.0 Tesla MR scanner (Philips Medical Systems, Andover, MA, USA), using the following parameters: repetition time, 6 s; echo time, 35 ms; slice thick, 6 mm; field of view, 240 × 240 mm2; matrix size, 64 × 64. A total of 250 functional images Non-specific serine/threonine protein kinase consisting of an echo planar scan were obtained for each

of the 22 slices over a 25-min period. Subjects kept their eyes closed during MR scanning. Realignment, normalization, and smoothing as preprocessing were performed for the MRI data using SPM 2 (Wellcome Trust Centre for Neuroimaging, London, UK).5 Head movement was corrected by realignment, the realigned images were moved into the same Montreal Neurological Institute space by normalization, and normalized images were smoothed with an 8-mm Gaussian spatial filter. Smoothed data were analyzed using GIFT v1.3d,6 a group ICA approach. First, setup was done, and a number of independent components from the data were extracted. Second, analysis was run and the result was visualized using the component explorer. Group ICA was applied to fMRI data during the first interval, saline infusion, and HCl infusion. The results were inspected manually to detect interesting components. Masks for region of interest analysis version 0.6.1. (Bender Institute of Neuroimaging, University of Giessen, Giessen, Germany)7 were used to identify the cerebral region of the interesting components. Subjects did not have any heartburn, and never pushed the response device. But, all the subjects were aware of the presence of the feeding tube in the esophagus during MR scanning. Two subjects felt the infusion of liquid.