The vestibulospinal nucleus is a locus of balance development

Abstract

Mature vertebrates maintain posture using vestibulospinal neurons that transform sensed instability into reflexive commands to spinal motor circuits. Postural stability improves across development. However, due to the complexity of terrestrial locomotion, vestibulospinal contributions to postural refinement in early life remain unexplored. Here we leveraged the relative simplicity of underwater locomotion to quantify the postural consequences of losing vestibulospinal neurons during development in larval zebrafish. By comparing posture at two timepoints, we discovered that later lesions of vestibulospinal neurons led to greater instability. Analysis of thousands of individual swim bouts revealed that lesions disrupted movement timing and corrective reflexes without impacting swim kinematics, particularly in older larvae. Using a generative model of swimming, we showed how these disruptions could account for the increased postural variability at both timepoints. Finally, late lesions disrupted the fin/trunk coordination observed in older larvae, linking vestibulospinal neurons to postural control schemes used to navigate in depth. Since later lesions were considerably more disruptive to postural stability, we conclude that vestibulospinal contributions to balance increase as larvae mature. Vestibulospinal neurons are highly conserved across vertebrates; we therefore propose that they are a substrate for developmental improvements to postural control.

Defects in exosome biogenesis are associated with sensorimotor defects in zebrafishvps4amutants

“…Hindbrain VS neurons, which directly innervate trunk motor neurons, have decreased neuronal activity in mutants. Recently it was shown that ablation of VS neurons leads to modest defects in posture in zebrafish larvae [98], suggesting that other vestibular circuits contribute to postural control. The reduced activation of the vestibulospinal pathway in vps4a T248I mutants may therefore only partially account for the inability to maintain an upright posture.…”

“…Hindbrain VS neurons, which directly innervate trunk motor neurons, have decreased neuronal activity in mutants. Recently it was shown that ablation of VS neurons leads to modest defects in posture in zebrafish larvae [98],…”