Tu1797 The Adoptive Transfer of Anxiety and Gut Dysfunction From IBS Patients to Axenic Mice Through Microbiota Transplantation

Studies of the effect of esophageal sensory stimulation on brain functional connectivity using magnetic resonance imaging (fc-MRI) requires insertion of perfusion or balloon catheters. The contribution of the presence of these catheters themselves on observed brain connectivity changes has not been systematically studied. Aim: To determine the effect of the presence of a catheter within the esophagus on a priori selected regional brain connectivity in healthy and patient volunteers. Methods: In 14 controls (7 female, age 27±4 years) and 12 nonerosive reflux disease (NERD) patients (6 female, age 46±5 years), fc-MRI data of amygdala connectivity to the rest of the brain were gathered during two 9-minute scans, one scan without transnasal esophageal intubation and one scan with esophageal intubation. Functional connectivity was quantified by the correlation coefficient (CC) between average fcMRI time series (seeds) in two spherical volumes centered in each of the right and left amygdala and time series of all fc-MRI volume elements (voxels) across the entire brain. The amygdala seeds were centered at the locations identified by the MNI atlas. Group analysis was performed using unpaired t-tests (with cluster size Monte Carlo simulation to correct for multiple comparison) of correlation coefficients to test amygdala-cortical connectivity differences across NERD patients and healthy subjects. Results: Amygdala connectivity was characterized by strong connections to the right and left superior temporal gyrus. The presence of esophageal catheter in the healthy controls resulted in significant differences in both left and right amygdala connectivity to the left superior temporal gyrus (Figure 1, p<0.001, corrected). No significant catheter effect was observed in the NERD patients. Presence of the catheter also effected the between group comparisons showing significant differences in amygdala connectivity. In the resting state without the catheter present, significant differences in both right and left amygdala connectivity to the right superior temporal gyrus were seen between the two groups (p<0,001, corrected). In the presence of catheter, significant differences were limited to the right amygdala connectivity to the right superior temporal gyrus (p<0,001, corrected). Conclusions: Pharyngo-esophageal stimulation by the presence of a catheter alters the functional connectivity of the amygdala in healthy controls. This response is absent in NERD patients which may represent a state of pre-existing maximum neural activity and associated BOLD signal alterations (ceiling effect). Furthermore, the presence of an esophageal catheter can affect the findings of comparative analyses between groups. This possibility needs to be taken into account when interpreting resting and non-resting state connectivity data involving esophageal stimulation.