title: Selective Inhibition Mediates the Sequential Recruitment of Motor Pools.
abstract: Locomotor systems generate diverse motor patterns to produce the movements underlying behavior, requiring that motor neurons be recruited at various phases of the locomotor cycle. Reciprocal inhibition produces alternating motor patterns; however, the mechanisms that generate other phasic relationships between intrasegmental motor pools are unknown. Here, we investigate one such motor pattern in the Drosophila larva, using a multidisciplinary approach including electrophysiology and ssTEM-based circuit reconstruction. We find that two motor pools that are sequentially recruited during locomotion have identical excitable properties. In contrast, they receive input from divergent premotor circuits. We find that this motor pattern is not orchestrated by differential excitatory input but by a GABAergic interneuron acting as a delay line to the later-recruited motor pool. Our findings show how a motor pattern is generated as a function of the modular organization of locomotor networks through segregation of inhibition, a potentially general mechanism for sequential motor patterns.
authors.affiliation: HHMI Janelia Research Campus, Ashburn, VA 20147, USA; Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK. Electronic address: zwartm@janelia.hhmi.org.
authors.forename: Maarten F
authors.initials: MF
authors.lastname: Zwart
authors.affiliation: HHMI Janelia Research Campus, Ashburn, VA 20147, USA.
authors.forename: Stefan R
authors.initials: SR
authors.lastname: Pulver
authors.affiliation: HHMI Janelia Research Campus, Ashburn, VA 20147, USA.
authors.forename: James W
authors.initials: JW
authors.lastname: Truman
authors.affiliation: HHMI Janelia Research Campus, Ashburn, VA 20147, USA.
authors.forename: Akira
authors.initials: A
authors.lastname: Fushiki
authors.affiliation: HHMI Janelia Research Campus, Ashburn, VA 20147, USA.
authors.forename: Richard D
authors.initials: RD
authors.lastname: Fetter
authors.affiliation: HHMI Janelia Research Campus, Ashburn, VA 20147, USA. Electronic address: cardonaa@janelia.hhmi.org.
authors.forename: Albert
authors.initials: A
authors.lastname: Cardona
authors.affiliation: Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK.
authors.forename: Matthias
authors.initials: M
authors.lastname: Landgraf
mesh_terms: D000818:Animals; D004331:Drosophila melanogaster / Q000166:cytology / Q000502:physiology; D059330:GABAergic Neurons / Q000502:physiology; D007395:Interneurons / Q000502:physiology; D007814:Larva / Q000166:cytology / Q000502:physiology; D008124:Locomotion / Q000502:physiology; D009046:Motor Neurons / Q000502:physiology*; D009433:Neural Inhibition / Q000502:physiology*; D009434:Neural Pathways / Q000502:physiology*