A BODY–BRAIN CIRCUIT FOR VIBROTACTILE INTEROCEPTIVE AWARENESS

Interoception is classically defined as the sensing of internal physiological states, yet the body also generates rich mechanical signals—including vibration arising from skeletal, muscular, and visceral dynamics. How such internally generated vibrotactile signals propagate through the body, are encoded by the nervous system, and give rise to perceptual awareness remains largely unexplored. Here, we establish a mechanistic framework for vibrotactile interoceptive awareness using a mouse psychophysics paradigm in which an implanted magnet generates controlled vibration within the rib cage, spine, or gut. Mice reliably perform a detection task reporting the presence of internal vibration, enabling quantitative assessment of perceptual sensitivity across internal anatomical sites. To characterize the physical substrate of this sensation, we quantified the frequency spectrum and power propagation of internal organ vibration using accelerometers, laser vibrometry, and high-speed video tracking at the skin, bones, and internal organs. At the neural level, fiber-based electrophysiology demonstrates robust encoding of internal vibrotactile signals in peripheral afferents. To identify the central ascending pathway supporting perception, we performed in vivo two-photon imaging of somatosensory brainstem nuclei, revealing reliable responses to internal vibration. Causal perturbations using chemogenetic and optogenetic inhibition show that both neural activity and behavioral detection critically depend on the dorsal column–medial lemniscus pathway, indicating that internal vibration is transmitted through canonical tactile ascending circuits rather than a distinct visceral pathway. Together, these results define a body–brain circuit linking internal biomechanics, somatosensory encoding, and perceptual report, demonstrating that internally generated mechanical vibration constitutes a behaviorally accessible interoceptive signal.