title: Descending Command Neurons in the Brainstem that Halt Locomotion.
abstract: The episodic nature of locomotion is thought to be controlled by descending inputs from the brainstem. Most studies have largely attributed this control to initiating excitatory signals, but little is known about putative commands that may specifically determine locomotor offset. To link identifiable brainstem populations to a potential locomotor stop signal, we used developmental genetics and considered a discrete neuronal population in the reticular formation: the V2a neurons. We find that those neurons constitute a major excitatory pathway to locomotor areas of the ventral spinal cord. Selective activation of V2a neurons of the rostral medulla stops ongoing locomotor activity, owing to an inhibition of premotor locomotor networks in the spinal cord. Moreover, inactivation of such neurons decreases spontaneous stopping in vivo. Therefore, the V2a "stop neurons" represent a glutamatergic descending pathway that favors immobility and may thus help control the episodic nature of locomotion.
authors.affiliation: Mammalian Locomotor Laboratory, Department of Neuroscience, Karolinska Institutet, 17177 Stockholm, Sweden; Paris-Saclay Institute of Neuroscience, UMR 9197 - CNRS and Université-Paris 11, 91190 Gif-sur-Yvette, France. Electronic address: julien.bouvier@inaf.cnrs-gif.fr.
authors.forename: Julien
authors.initials: J
authors.lastname: Bouvier
authors.affiliation: Mammalian Locomotor Laboratory, Department of Neuroscience, Karolinska Institutet, 17177 Stockholm, Sweden.
authors.forename: Vittorio
authors.initials: V
authors.lastname: Caggiano
authors.affiliation: Mammalian Locomotor Laboratory, Department of Neuroscience, Karolinska Institutet, 17177 Stockholm, Sweden.
authors.forename: Roberto
authors.initials: R
authors.lastname: Leiras
authors.affiliation: Mammalian Locomotor Laboratory, Department of Neuroscience, Karolinska Institutet, 17177 Stockholm, Sweden.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Caldeira
authors.affiliation: Mammalian Locomotor Laboratory, Department of Neuroscience, Karolinska Institutet, 17177 Stockholm, Sweden.
authors.forename: Carmelo
authors.initials: C
authors.lastname: Bellardita
authors.affiliation: Institute of Physiology, Christian Albrechts University of Kiel, 24098 Kiel, Germany.
authors.forename: Kira
authors.initials: K
authors.lastname: Balueva
authors.affiliation: Mammalian Locomotor Laboratory, Department of Neuroscience, Karolinska Institutet, 17177 Stockholm, Sweden.
authors.forename: Andrea
authors.initials: A
authors.lastname: Fuchs
authors.affiliation: Mammalian Locomotor Laboratory, Department of Neuroscience, Karolinska Institutet, 17177 Stockholm, Sweden. Electronic address: ole.kiehn@ki.se.
authors.forename: Ole
authors.initials: O
authors.lastname: Kiehn
mesh_terms: D000818:Animals; D001933:Brain Stem / Q000166:cytology / Q000502:physiology*; D063226:Central Pattern Generators / Q000502:physiology; D008124:Locomotion; D008164:Luminescent Proteins / Q000032:analysis; D051379:Mice; D009434:Neural Pathways; D009474:Neurons / Q000166:cytology*; D013116:Spinal Cord / Q000502:physiology; D000097573:Red Fluorescent Protein
chemical_list: D008164:Luminescent Proteins; D000097573:Red Fluorescent Protein