Conducting this study necessitates the use of human subjects for research purposes. In total, the investigators will recruit 120 IBS subjects, 70 age-matched HCs, and 100 UC subjects. During the initial screening visit, the subject will complete a physical examination, a short psychological evaluation (MINI+), a pressure & heat sensitivity test, a quick blood draw, and a set of questionnaires. In total, this baseline visit will take roughly two hours.