title: Characterization of long descending premotor propriospinal neurons in the spinal cord.
abstract: The motor function of the spinal cord requires the computation of the local neuronal circuits within the same segments as well as the long-range coordination of different spinal levels. Implicated players in this process are the propriospinal neurons (PPNs) that project their axons across different levels of the spinal cord. However, their cellular, molecular, and functional properties remain unknown. Here we use a recombinant rabies virus-based method to label a specific type of long-projecting premotor PPNs in the mouse upper spinal cord that are monosynaptically connected to the motor neurons in the lumbar spinal cord. With a whole spinal cord imaging method, we find that these neurons are distributed along the entire length of the upper spinal cord with more in the lower thoracic levels. Among them, a subset of thoracic PPNs receive substantial numbers of sensory inputs, suggesting a function in coordinating the activity of trunk and hindlimb muscles. Although many PPNs in the cervical and thoracic spinal cord receive the synaptic inputs from corticospinal tract or serotonergic axons, limited bouton numbers suggested that these supraspinal inputs might not be major regulators of the PPNs in intact animals. Molecularly, these PPNs appear to be distinct from other known premotor interneurons, but some are derived from Chx10+ lineages. This study provides an anatomical basis for further exploring different functions of PPNs.
authors.affiliation: F.M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts 02115.
authors.forename: Yingchun
authors.initials: Y
authors.lastname: Ni
authors.affiliation: F.M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts 02115.
authors.forename: Homaira
authors.initials: H
authors.lastname: Nawabi
authors.affiliation: F.M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts 02115.
authors.forename: Xuefeng
authors.initials: X
authors.lastname: Liu
authors.affiliation: F.M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts 02115.
authors.forename: Liu
authors.initials: L
authors.lastname: Yang
authors.affiliation: Howard Hughes Medical Institute, Department of Biology, Stanford University, Stanford, California 94305, and.
authors.forename: Kazunari
authors.initials: K
authors.lastname: Miyamichi
authors.affiliation: F.M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts 02115.
authors.forename: Andrea
authors.initials: A
authors.lastname: Tedeschi
authors.affiliation: F.M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts 02115.
authors.forename: Bengang
authors.initials: B
authors.lastname: Xu
authors.affiliation: Systems Neurobiology Laboratory, The Salk Institute for Biological Studies and Neurosciences Graduate Program, University of California, San Diego, La Jolla, California 92037.
authors.forename: Nicholas R
authors.initials: NR
authors.lastname: Wall
authors.affiliation: Systems Neurobiology Laboratory, The Salk Institute for Biological Studies and Neurosciences Graduate Program, University of California, San Diego, La Jolla, California 92037.
authors.forename: Edward M
authors.identifier: http://orcid.org/0000-0002-6366-5267
authors.initials: EM
authors.lastname: Callaway
authors.affiliation: F.M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts 02115, zhigang.he@childrens.harvard.edu.
authors.forename: Zhigang
authors.initials: Z
authors.lastname: He
mesh_terms: D000818:Animals; D005260:Female; D008297:Male; D051379:Mice; D009046:Motor Neurons / Q000166:cytology*; D009434:Neural Pathways / Q000166:cytology; D011712:Pyramidal Tracts / Q000166:cytology*; D011984:Sensory Receptor Cells / Q000166:cytology*; D013116:Spinal Cord / Q000166:cytology*