Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

Motor neurons in the central nervous system often lie in a continuous topographic map, where neurons that innervate different body parts are spatially intermingled. This is the case for the efferent neurons of the vagus nerve, which innervate diverse muscle and organ targets in the head and viscera for brain-body communication. It remains elusive how neighboring motor neurons with different fixed peripheral axon targets develop the separate somatodendritic (input) connectivity they need to generate spatially precise body control. Here, we show that vagus motor neurons in the zebrafish indeed generate spatially appropriate peripheral responses to focal sensory stimulation even when they are transplanted into ectopic positions within the topographic map, indicating that circuit refinement occurs after the establishment of coarse topography. Refinement depends on motor neuron synaptic transmission, suggesting that an experience-dependent periphery-to-brain feedback mechanism establishes specific input connectivity among intermingled motor populations.

DOI： 10.1016/j.celrep.2024.114740

PubMed

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Sensory axons projecting to the central nervous system are organized into topographic maps that represent the locations of sensory stimuli. In some sensory systems, even adjacent sensory axons are arranged topographically, forming "fine-scale" topographic maps. Although several broad molecular gradients are known to instruct coarse topography, we know little about the molecular signaling that regulates fine-scale topography at the level of two adjacent axons. Here, we provide evidence that trans-synaptic BMP signaling mediates local inter-neuronal communication to regulate fine-scale topography in the nociceptive system of Drosophila larvae. We first show that the topographic separation of the axon terminals of adjacent nociceptors requires their common postsynaptic target, the A08n neurons. This phenotype is recapitulated by knockdown of the BMP ligand, Dpp, in these neurons. In addition, removing the type-II BMP receptors or their effector (Mad transcription factor) in single nociceptors impairs the fine-scale topography, suggesting the contribution of BMP signaling originated from A08n. This signaling is likely mediated by phospho-Mad in the presynaptic terminals of nociceptors to ensure local inter-neuronal communication. Finally, reducing Dpp levels in A08n reduces the nociceptor-A08n synaptic contacts. Our data support that trans-synaptic BMP signaling establishes the fine-scale topography by facilitating the formation of topographically correct synapses. Local BMP signaling for synapse formation may be a developmental strategy that independently regulates neighboring axon terminals for fine-scale topography.Significance Statement Sensory axons projecting to the central nervous system (CNS) are organized spatially to represent the locations of sensory stimuli. This occurs even between adjacent sensory axons. While much has been learned about the rough spatial arrangement of sensory axons in the CNS, the molecular signaling that arranges two adjacent axons remains poorly understood. The present study shows that this process is regulated by local inter-neuronal communication via a trans-synaptic BMP signaling that facilitates the synapse formation of the sensory axons that are appropriately located.

DOI： 10.1523/ENEURO.0322-24.2024

PubMed

Authorship：Lead author,　Corresponding author   Language：English  

Motor neurons in the central nervous system often lie in a continuous topographic map, where neurons that innervate different body parts are spatially intermingled. This is the case for the efferent neurons of the vagus nerve, which innervate diverse muscle and organ targets in the head and viscera for brain-body communication. It remains elusive how neighboring motor neurons with different fixed peripheral axon targets develop the separate somatodendritic (input) connectivity they need to generate spatially precise body control. Here we show that vagus motor neurons in the zebrafish indeed generate spatially appropriate peripheral responses to focal sensory stimulation even when they are transplanted into ectopic positions within the topographic map, indicating that circuit refinement occurs after the establishment of coarse topography. Refinement depends on motor neuron synaptic transmission, suggesting that an experience-dependent periphery-to-brain feedback mechanism establishes specific input connectivity amongst intermingled motor populations.

DOI： 10.1101/2023.09.11.557289

PubMed

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Poster presentation