Article ID Journal Published Year Pages File Type
4321014 Neuron 2015 15 Pages PDF
Abstract

•Neural ensembles code the Aplysia locomotion motor program•Stable and rotational dynamics differentiate classes of ensemble•Different dynamical classes map to physically separate and discrete regions•Low-dimensional rotations of activity are recapitulated in physical space

SummaryThe 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.

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