title: Modular deconstruction reveals the dynamical and physical building blocks of a locomotion motor program.
abstract: The neural substrates of motor programs are only well understood for small, dedicated circuits. Here we investigate how a motor program is constructed within a large network. We imaged populations of neurons in the Aplysia pedal ganglion during execution of a locomotion motor program. We found that the program was built from a very small number of dynamical building blocks, including both neural ensembles and low-dimensional rotational dynamics. These map onto physically discrete regions of the ganglion, so that the motor program has a corresponding modular organization in both dynamical and physical space. Using this dynamic map, we identify the population potentially implementing the rhythmic pattern generator and find that its activity physically traces a looped trajectory, recapitulating its low-dimensional rotational dynamics. Our results suggest that, even in simple invertebrates, neural motor programs are implemented by large, distributed networks containing multiple dynamical systems.
authors.affiliation: Department of Neuroscience, The Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, IL 60064-3095, USA.
authors.forename: Angela M
authors.initials: AM
authors.lastname: Bruno
authors.affiliation: Department of Cell Biology and Anatomy, The Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, IL 60064-3095, USA. Electronic address: william.frost@rosalindfranklin.edu.
authors.forename: William N
authors.initials: WN
authors.lastname: Frost
authors.affiliation: Faculty of Life Sciences, University of Manchester, Manchester, M13 9PT, UK. Electronic address: mark.humphries@manchester.ac.uk.
authors.forename: Mark D
authors.initials: MD
authors.lastname: Humphries
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000818:Animals; D001048:Aplysia; D001921:Brain / Q000502:physiology*; D001931:Brain Mapping; D008124:Locomotion / Q000502:physiology*; D008959:Models, Neurological; D009046:Motor Neurons / Q000502:physiology*; D009415:Nerve Net / Q000502:physiology*; D017711:Nonlinear Dynamics
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