Cognitive neuroscience is increasingly moving beyond a brain-centric perspective to study the brain as part of an integrated organism. This chapter advocates for this paradigm shift by detailing how neural measures can be complemented with non-invasive recordings of peripheral physiological signals. We focus on three vital visceral rhythms—of the heart (~1 Hz), the lungs (~0.2–0.3 Hz), and the stomach (~0.05 Hz)—that provide tractable access to the continuous, bidirectional communication between the central and peripheral nervous systems. For each rhythm, we outline the underlying physiology, practical guidance for recording (e.g., electrocardiography, respiratory belts, electrogastrography), and key derived metrics (e.g., heart rate variability, respiratory phase, gastric amplitude). We then illustrate how these signals are used to investigate functional brain-body coupling, from heartbeat-evoked potentials and respiration-locked neural oscillations to stomach-brain synchronization. By integrating these bodily rhythms with neural measures, researchers can gain a more holistic understanding of how peripheral physiology shapes affective, cognitive, and perceptual functions.