Long ascending propriospinal neurons provide flexible, context-specific control of interlimb coordination
Amanda M Pocratsky,
Courtney T Shepard,
Johnny R Morehouse,
Darlene A Burke,
Amberley S Riegler,
Josiah T Hardin,
Jason E Beare,
Casey Hainline,
Gregory JR States,
Brandon L Brown,
Scott R Whittemore,
David SK Magnuson
Affiliations
Amanda M Pocratsky
Department of Anatomical Sciences and Neurobiology, University of Louisville, Louisville, United States; Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, United States
Courtney T Shepard
Department of Anatomical Sciences and Neurobiology, University of Louisville, Louisville, United States; Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, United States
Johnny R Morehouse
Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, United States; Department of Neurological Surgery, University of Louisville, Louisville, United States
Darlene A Burke
Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, United States; Department of Neurological Surgery, University of Louisville, Louisville, United States
Amberley S Riegler
Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, United States; Department of Neurological Surgery, University of Louisville, Louisville, United States
Josiah T Hardin
Speed School of Engineering, University of Louisville, Louisville, United States
Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, United States; Cardiovascular Innovation Institute, Department of Physiology and Biophysics, University of Louisville, Louisville, United States
Casey Hainline
Speed School of Engineering, University of Louisville, Louisville, United States
Gregory JR States
Department of Anatomical Sciences and Neurobiology, University of Louisville, Louisville, United States; Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, United States
Brandon L Brown
Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, United States
Department of Anatomical Sciences and Neurobiology, University of Louisville, Louisville, United States; Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, United States; Department of Neurological Surgery, University of Louisville, Louisville, United States
Department of Anatomical Sciences and Neurobiology, University of Louisville, Louisville, United States; Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, United States; Department of Neurological Surgery, University of Louisville, Louisville, United States; Speed School of Engineering, University of Louisville, Louisville, United States
Within the cervical and lumbar spinal enlargements, central pattern generator (CPG) circuitry produces the rhythmic output necessary for limb coordination during locomotion. Long propriospinal neurons that inter-connect these CPGs are thought to secure hindlimb-forelimb coordination, ensuring that diagonal limb pairs move synchronously while the ipsilateral limb pairs move out-of-phase during stepping. Here, we show that silencing long ascending propriospinal neurons (LAPNs) that inter-connect the lumbar and cervical CPGs disrupts left-right limb coupling of each limb pair in the adult rat during overground locomotion on a high-friction surface. These perturbations occurred independent of the locomotor rhythm, intralimb coordination, and speed-dependent (or any other) principal features of locomotion. Strikingly, the functional consequences of silencing LAPNs are highly context-dependent; the phenotype was not expressed during swimming, treadmill stepping, exploratory locomotion, or walking on an uncoated, slick surface. These data reveal surprising flexibility and context-dependence in the control of interlimb coordination during locomotion.
