Esophageal acid stimulation alters insular cortex functional connectivity in gastroesophageal reflux disease

R. M. Siwiec, A. Babaei, M. Kern, E. A. Samuel, S. J. Li, Reza Shaker

Research output: Contribution to journalArticle

3 Scopus citations

Abstract

Background: The insula plays a significant role in the interoceptive processing of visceral stimuli. We have previously shown that gastroesophageal reflux disease (GERD) patients have increased insular cortex activity during esophageal stimulation, suggesting a sensitized esophago-cortical neuraxis. However, information regarding the functional connectivity (FC) of the insula during visceral stimulation is lacking. The primary aim of this study was to investigate the FC of insular subregions during esophageal acid stimulation. Methods: Functional imaging data were obtained from 12 GERD patients and 14 healthy subjects during four steady state conditions: (i) presence of transnasal esophageal catheter (pre-infusion); (ii) neutral solution; (iii) acid infusion; (iv) presence of transnasal esophageal catheter following infusions (post-infusion). The insula was parcellated into six regions of interest. FC maps between each insular ROI and interoceptive regions were created. Differences in FC between GERD patients and healthy subjects were determined across the 4 study conditions. Key Results: All GERD patients experienced heartburn during and after esophageal acidification. Significant differences between GERD patients and healthy subjects were seen in: (i) insula-thalamic FC (neutral solution infusion, acid infusion, post-infusion); (ii) insula-amygdala FC (acid infusion, post-infusion); (iii) insula-hippocampus and insula-cingulate FC (post-infusion). Conclusions & Inferences: Esophageal stimulation in GERD patients revealed significant insular cortex FC differences with regions involved in viscerosensation and interoception. The results of our study provide further evidence that the insula, located at the transition of afferent physiologic information to human feelings, is essential for both visceral homeostasis and the experience of heartburn in GERD patients. The insula plays a significant role in the interoceptive processing of visceral stimuli. The aim of the study was to investigate the functional connectivity (FC) of the insula with previously implicated cortical areas involved in emotional awareness and subjective evaluation of internal physiologic conditions in patients with GERD during esophageal stimulation. FC between insular subregions and a priori defined interoceptive regions was compared between GERD patients and healthy controls during four steady state conditions: (i) presence of transnasal esophageal catheter (pre-infusion); (ii) neutral solution infusion; (iii) acid infusion; (iv) presence of transnasal esophageal catheter following infusions (post-infusion). Significant differences were found between GERD patients and healthy controls in: (i) insula-thalamic FC (neutral solution infusion, acid infusion, post-infusion); (ii) insula-amygdala FC (acid infusion, post-infusion); and (iii) insula-hippocampus and insula-cingulate FC (post-infusion). Esophageal acid stimulation in patients with GERD produces significant insular cortex FC differences with regions underlying interoception and viscerosensation.

Original languageEnglish (US)
Pages (from-to)201-211
Number of pages11
JournalNeurogastroenterology and Motility
Volume27
Issue number2
DOIs
StatePublished - Feb 1 2015

Keywords

  • Heartburn
  • Interoception
  • Viscerosensation

ASJC Scopus subject areas

  • Endocrine and Autonomic Systems
  • Gastroenterology
  • Physiology

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