title: Distinct limb and trunk premotor circuits establish laterality in the spinal cord.
abstract: Movement coordination between opposite body sides relies on neuronal circuits capable of controlling muscle contractions according to motor commands. Trunk and limb muscles engage in distinctly lateralized behaviors, yet how regulatory spinal circuitry differs is less clear. Here, we intersect virus technology and mouse genetics to unravel striking distribution differences of interneurons connected to functionally distinct motor neurons. We find that premotor interneurons conveying information to axial motor neurons reside in symmetrically balanced locations while mostly ipsilateral premotor interneurons synapse with limb-innervating motor neurons, especially those innervating more distal muscles. We show that observed distribution differences reflect specific premotor interneuron subpopulations defined by genetic and neurotransmitter identity. Synaptic input across the midline reaches axial motor neurons preferentially through commissural axon arborization, and to a lesser extent, through midline-crossing dendrites capturing contralateral synaptic input. Together, our findings provide insight into principles of circuit organization underlying weighted lateralization of movement.
authors.affiliation: Biozentrum, Department of Cell Biology, University of Basel, Klingelbergstrasse 70, 4056 Basel, Switzerland; Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland.
authors.forename: Cyrill
authors.initials: C
authors.lastname: Goetz
authors.affiliation: Biozentrum, Department of Cell Biology, University of Basel, Klingelbergstrasse 70, 4056 Basel, Switzerland; Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland.
authors.forename: Chiara
authors.initials: C
authors.lastname: Pivetta
authors.affiliation: Biozentrum, Department of Cell Biology, University of Basel, Klingelbergstrasse 70, 4056 Basel, Switzerland; Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland. Electronic address: silvia.arber@unibas.ch.
authors.forename: Silvia
authors.initials: S
authors.lastname: Arber
mesh_terms: D000818:Animals; D001369:Axons / Q000502:physiology*; D066294:Commissural Interneurons / Q000502:physiology*; D003712:Dendrites / Q000502:physiology*; D005121:Extremities / Q000294:innervation; D007839:Functional Laterality / Q000502:physiology*; D007395:Interneurons / Q000502:physiology; D051379:Mice; D009046:Motor Neurons / Q000378:metabolism / Q000502:physiology*; D013116:Spinal Cord / Q000502:physiology*; D009435:Synaptic Transmission / Q000502:physiology*; D060726:Torso / Q000294:innervation