Abstract:
A main function of the stomach is to accommodate and break down the ingested food and further push it to the small intestine for nutrient absorption. To carry out this function, gastric smooth muscle cells (SMC) maintain and coordinate their contractions and relaxations across regions of the stomach. The pattern of muscle activity is intrinsically paced by a propagating electrical rhythm initiated by the interstitial cells of Cajal (ICC) and extrinsically regulated by the brain through peripheral nerves innervating the stomach. The ICC-initiated electrical slow wave paces the peristaltic mechanical wave through the active coupling between ICC and SMC (or the electromechanical coupling). The strength of this coupling is up- or down-regulated by the brain through descending vagal nerves, which selectively innervate different types of enteric motor neurons that either excite or inhibit SMC, respectively. The neural control of gastric muscle activity varies across times and conditions to support a wide range of ingestive and digestive processes. In this thesis research, sensors, devices, and signal processing methods were developed for simultaneous recording and real-time analysis of gastric electrical and mechanical activity. Experiments with rats were performed to demonstrate the feasibility of concurrent strain and electrical recordings in both acute and chronic settings. The relationships between the recorded electrical and mechanical activities were evaluated minute-by-minute in terms of their phase, frequency, and amplitude. The electromechanical coupling was stronger and less variable after animals consumed a test meal (or in the fed state) than when the stomach was empty following overnight deprivation of food and drink (or in the fasted state). This finding suggests that the electromechanical coupling may serve as a quantitative biomarker that reports on the real-time neural control of gastric motility, discriminates different gastric states, and by doing so, provides a feedback signal for closed-loop neuromodulation of the stomach. The techniques and findings described in this thesis merit future translational studies to further advance the understanding of gastric physiology and pathophysiology, as well as the diagnosis and treatment of prevailing functional gastrointestinal disorders.

Committee Chair(s):
Dr. Zhongming Liu

Zoom Link: https://umich.zoom.us/j/95286593974
Meeting ID: 952 8659 3974
Passcode: 590590