title: The speed-curvature power law in Drosophila larval locomotion.
abstract: We report the discovery that the locomotor trajectories of Drosophila larvae follow the power-law relationship between speed and curvature previously found in the movements of human and non-human primates. Using high-resolution behavioural tracking in controlled but naturalistic sensory environments, we tested the law in maggots tracing different trajectory types, from reaching-like movements to scribbles. For most but not all flies, we found that the law holds robustly, with an exponent close to three-quarters rather than to the usual two-thirds found in almost all human situations, suggesting dynamic effects adding on purely kinematic constraints. There are different hypotheses for the origin of the law in primates, one invoking cortical computations, another viscoelastic muscle properties coupled with central pattern generators. Our findings are consistent with the latter view and demonstrate that the law is possible in animals with nervous systems orders of magnitude simpler than in primates. Scaling laws might exist because natural selection favours processes that remain behaviourally efficient across a wide range of neural and body architectures in distantly related species.
authors.affiliation: Laboratory of Neuromotor Physiology, IRCCS Santa Lucia Foundation, Via Ardeatina 306, 00179 Rome, Italy.
authors.forename: Myrka
authors.identifier: 0000-0001-7100-7582
authors.initials: M
authors.lastname: Zago
authors.affiliation: Laboratory of Neuromotor Physiology, IRCCS Santa Lucia Foundation, Via Ardeatina 306, 00179 Rome, Italy.|Department of Systems Medicine, Medical School, University of Rome Tor Vergata, Via Montpellier 1, 00133 Rome, Italy.|Centre of Space Biomedicine, University of Rome Tor Vergata, Via Montpellier 1, 00133 Rome, Italy.
authors.forename: Francesco
authors.identifier: 0000-0003-0896-7315
authors.initials: F
authors.lastname: Lacquaniti
authors.affiliation: Behavior of Organisms Laboratory, Instituto de Neurociencias CSIC-UMH, Av. Ramón y Cajal, Alacant, Spain a.gomezmarin@umh.es.
authors.forename: Alex
authors.identifier: 0000-0003-2764-2583
authors.initials: A
authors.lastname: Gomez-Marin
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D002087:Butyrates / Q000494:pharmacology; D002633:Chemotaxis; D004331:Drosophila melanogaster / Q000502:physiology*; D007814:Larva / Q000502:physiology; D008124:Locomotion; D008954:Models, Biological
chemical_list: D002087:Butyrates; C045572:ethyl butyrate
keywords: Drosophila; locomotion; motor control; power law