A spinal organ of proprioception for integrated motor action feedback

Proprioception is essential for behavior and provides a sense of our body movements in physical space. Proprioceptor organs are thought to be only in the periphery. Whether the central nervous system can intrinsically sense its own movement remains unclear. Here we identify a segmental organ of proprioception in the adult zebrafish spinal cord, which is embedded by intraspinal mechanosensory neurons expressing Piezo2 channels. These cells are late-born, inhibitory, commissural neurons with unique molecular and physiological profiles reflecting a dual sensory and motor function. The central proprioceptive organ locally detects lateral body movements during locomotion and provides direct inhibitory feedback onto rhythm-generating interneurons responsible for the central motor program. This dynamically aligns central pattern generation with movement outcome for efficient locomotion. Our results demonstrate that a central proprioceptive organ monitors self-movement using hybrid neurons that merge sensory and motor entities into a unified network. [Display omitted] •A central organ of proprioception exists in the spinal cord•Piezo2-expressing mechanosensitive neurons sense lateral bending of spinal cord•These are inhibitory commissural neurons targeting the locomotor rhythm generator•Intraspinal proprioceptive feedback aligns movements with motor commands Picton et al. reveal a central organ of proprioception embedded with Piezo2-expressing mechanosensitive neurons in adult zebrafish. These neurons are endowed with a hybrid function as sensory neurons and commissural inhibitory neurons, merging proprioceptive feedback and locomotor rhythm generation into a unified sensorimotor circuit.