The role of intraspinal sensory neurons in the control of quadrupedal locomotion

Abstract

From swimming to walking and flying, animals have evolved specific locomotor strategies to thrive in different habitats. All types of locomotion depend on integration of motor commands and sensory information to generate precise movements. Cerebrospinal fluid-contacting neurons (CSF-cN) constitute a vertebrate sensory system that monitors CSF composition and flow. In fish, CSF-cN modulate swimming activity in response to changes in pH and bending of the spinal cord, yet their role in higher vertebrates remains unknown. We used mouse genetics to study their function in quadrupedal locomotion and found that CSF-cN are directly integrated into spinal motor circuits by forming connections with motor neurons and premotor interneurons. Elimination of CSF-cN selectively perturbs the accuracy of foot placement required for skilled movements at the balance beam and horizontal ladder. These results identify an important role for mouse CSF-cN in adaptive motor control and indicate that this sensory system evolved a novel function from lower vertebrates to accommodate the biomechanical requirements of terrestrial locomotion.