The Mesencephalic Locomotor Region Recruits V2a Reticulospinal Neurons to Drive Forward Locomotion in Larval Zebrafish

Authors

Martin Carbo-Tano
Mathilde Lapoix
Xinyu Jia
Olivier Thouvenin
Marco Pascucci
François Auclair
Feng B Quan
Shahad Albadri
Vernie Aguda
Younes Farouj
Elizabeth M C Hillman
Ruben Portugues
Filippo Del Bene
Tod R Thiele
Réjean Dubuc
Claire Wyart

Publication Date

10-1-2023

Journal

Nature Neuroscience

Abstract

The mesencephalic locomotor region (MLR) is a brain stem area whose stimulation triggers graded forward locomotion. How MLR neurons recruit downstream vsx2+ (V2a) reticulospinal neurons (RSNs) is poorly understood. Here, to overcome this challenge, we uncovered the locus of MLR in transparent larval zebrafish and show that the MLR locus is distinct from the nucleus of the medial longitudinal fasciculus. MLR stimulations reliably elicit forward locomotion of controlled duration and frequency. MLR neurons recruit V2a RSNs via projections onto somata in pontine and retropontine areas, and onto dendrites in the medulla. High-speed volumetric imaging of neuronal activity reveals that strongly MLR-coupled RSNs are active for steering or forward swimming, whereas weakly MLR-coupled medullary RSNs encode the duration and frequency of the forward component. Our study demonstrates how MLR neurons recruit specific V2a RSNs to control the kinematics of forward locomotion and suggests conservation of the motor functions of V2a RSNs across vertebrates.

Keywords

Animals, Zebrafish, Larva, Mesencephalon, Locomotion, Neurons, Spinal Cord, Electric Stimulation

Comments

Supplementary Materials

PMID: 37667039