Birthdate aligns vestibular sensory neurons with central and motor partners across a sensorimotor reflex circuit for gaze stabilization

Abstract

Developing populations of connected neurons often share spatial and/or temporal features that anticipate their assembly. A unifying spatiotemporal motif might link sensory, central, and motor populations that comprise an entire circuit. In the sensorimotor reflex circuit that stabilizes vertebrate gaze, central and motor partners are paired in time (birthdate) and space (dorso-ventral). To determine if birthdate and/or dorso-ventral organiza-tion could align the entire circuit, we measured the spatial and temporal development of the sensory circuit node: the vestibular ganglion neurons. We discovered that progressive dorsal-to-ventral organization closely predicts vestibular ganglion development, with additional organization along its functional (rostrocaudal) axis. With an acute optical lesion and calcium imaging paradigm, we found that this common spatiotemporal axis anticipated functional sensory-to-central partner matching. We propose a "first-come, first-served" model in which birth-date organizes and assembles the sensory, central, and motor populations that comprise the gaze stabilization circuit, a general strategy for poly-synaptic circuit assembly across embryonically-diverse neural populations. SUMMARY STATEMENTCircuit nodes often develop along common axes. We find that a "first-come, first-served" temporal rule underscores the organization of a canonical sensorimotor circuit for gaze stabilization, simplifying poly-synaptic assembly.