Understanding how the circuitry that controls locomotor behavior is established during development can contribute to designing therapies aimed at restoring these functions if they are lost due to disease. As published in the Sep 2 Neuron, scientists led by Samuel Pfaff at the Salk Institute in La Jolla, California, developed a novel approach for real-time visualization of neuronal activity based on two-photon microscopy and the genetically-encoded fluorescent calcium sensor, GCaMP6f. Using this approach, first-author Christopher Hinckley and colleagues were able to visualize the characteristic synchronous firing of subgroups of lumbar spinal motor neurons (MNs) in response to activation of the locomotor central pattern generator (CPG), a network of neurons that ultimately drives rhythmic muscle activity for walking. By manipulating the genetic and spatial identity of subtypes of lumbar MNs, the researchers were able to identify which characteristics of the circuitry are genetically determined and which are established based on spatial cues. These findings reveal some of the complex rules that govern wiring of locomotor circuits in the spinal cord.
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Hinckley CA, Alaynick WA, Gallarda BW, Hayashi M, Hilde KL, Driscoll SP, Dekker JD, Tucker HO, Sharpee TO, Pfaff SL. Spinal Locomotor Circuits Develop Using Hierarchical Rules Based on Motorneuron Position and Identity. Neuron. 2015 Sep 2;87(5):1008-21. [Pubmed].