title: Imaging fictive locomotor patterns in larval Drosophila.
abstract: We have established a preparation in larval Drosophila to monitor fictive locomotion simultaneously across abdominal and thoracic segments of the isolated CNS with genetically encoded Ca(2+) indicators. The Ca(2+) signals closely followed spiking activity measured electrophysiologically in nerve roots. Three motor patterns are analyzed. Two comprise waves of Ca(2+) signals that progress along the longitudinal body axis in a posterior-to-anterior or anterior-to-posterior direction. These waves had statistically indistinguishable intersegmental phase delays compared with segmental contractions during forward and backward crawling behavior, despite being ∼10 times slower. During these waves, motor neurons of the dorsal longitudinal and transverse muscles were active in the same order as the muscle groups are recruited during crawling behavior. A third fictive motor pattern exhibits a left-right asymmetry across segments and bears similarities with turning behavior in intact larvae, occurring equally frequently and involving asymmetry in the same segments. Ablation of the segments in which forward and backward waves of Ca(2+) signals were normally initiated did not eliminate production of Ca(2+) waves. When the brain and subesophageal ganglion (SOG) were removed, the remaining ganglia retained the ability to produce both forward and backward waves of motor activity, although the speed and frequency of waves changed. Bilateral asymmetry of activity was reduced when the brain was removed and abolished when the SOG was removed. This work paves the way to studying the neural and genetic underpinnings of segmentally coordinated motor pattern generation in Drosophila with imaging techniques.
authors: School of Psychology and Neuroscience, University of St Andrews, St Andrews, United Kingdom; Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, Virginia sp96@st-andrews.ac.uk.
authors: Stefan R
authors: SR
authors: Pulver
authors: Department of Zoology, University of Cambridge, Cambridge, United Kingdom; and.
authors: Timothy G
authors: TG
authors: Bayley
authors: Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, Virginia.
authors: Adam L
authors: AL
authors: Taylor
authors: Department of Zoology, University of Cambridge, Cambridge, United Kingdom; and.
authors: Jimena
authors: J
authors: Berni
authors: Department of Zoology, University of Cambridge, Cambridge, United Kingdom; and.
authors: Michael
authors: M
authors: Bate
authors: Department of Zoology, University of Cambridge, Cambridge, United Kingdom; and.
authors: Berthold
authors: B
authors: Hedwig
mesh_terms: D000200:Action Potentials; D000818:Animals; D001921:Brain / Q000502:physiology*; D020013:Calcium Signaling; D004331:Drosophila melanogaster; D017952:Ganglia, Invertebrate / Q000502:physiology*; D007814:Larva / Q000502:physiology; D008124:Locomotion / Q000502:physiology*; D009046:Motor Neurons / Q000502:physiology*; D061848:Optical Imaging / Q000379:methods*
keywords: calcium imaging; central pattern generator; intersegmental coordination; locomotion; neuroethology