Search our Database of Scientific Publications and Authors

I’m looking for a
    Organization of left-right coordination of neuronal activity in the mammalian spinal cord: Insights from computational modelling.
    J Physiol 2015 Jun;593(11):2403-26
    Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA, USA.
    Key Points: Coordination of neuronal activity between left and right sides of the mammalian spinal cord is provided by several sets of commissural interneurons (CINs) whose axons cross the midline. Genetically identified inhibitory V0D and excitatory V0V CINs and ipsilaterally projecting excitatory V2a interneurons were shown to secure left-right alternation at different locomotor speeds. We have developed computational models of neuronal circuits in the spinal cord that include left and right rhythm-generating centres interacting bilaterally via three parallel pathways mediated by V0D , V2a-V0V and V3 neuron populations. The models reproduce the experimentally observed speed-dependent left-right coordination in normal mice and the changes in coordination seen in mutants lacking specific neuron classes. The models propose an explanation for several experimental results and provide insights into the organization of the spinal locomotor network and parallel CIN pathways involved in gait control at different locomotor speeds.

    Abstract: Different locomotor gaits in mammals, such as walking or galloping, are produced by coordinated activity in neuronal circuits in the spinal cord. Coordination of neuronal activity between left and right sides of the cord is provided by commissural interneurons (CINs), whose axons cross the midline. In this study, we construct and analyse two computational models of spinal locomotor circuits consisting of left and right rhythm generators interacting bilaterally via several neuronal pathways mediated by different CINs. The CIN populations incorporated in the models include the genetically identified inhibitory (V0D ) and excitatory (V0V ) subtypes of V0 CINs and excitatory V3 CINs. The model also includes the ipsilaterally projecting excitatory V2a interneurons mediating excitatory drive to the V0V CINs. The proposed network architectures and CIN connectivity allow the models to closely reproduce and suggest mechanistic explanations for several experimental observations. These phenomena include: different speed-dependent contributions of V0D and V0V CINs and V2a interneurons to left-right alternation of neural activity, switching gaits between the left-right alternating walking-like activity and the left-right synchronous hopping-like pattern in mutants lacking specific neuron classes, and speed-dependent asymmetric changes of flexor and extensor phase durations. The models provide insights into the architecture of spinal network and the organization of parallel inhibitory and excitatory CIN pathways and suggest explanations for how these pathways maintain alternating and synchronous gaits at different locomotor speeds. The models propose testable predictions about the neural organization and operation of mammalian locomotor circuits.

    Similar Publications

    Central control of interlimb coordination and speed-dependent gait expression in quadrupeds.
    J Physiol 2016 Dec 8;594(23):6947-6967. Epub 2016 Nov 8.
    Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA, USA.
    Key Points: Quadrupeds express different gaits depending on speed of locomotion. Central pattern generators (one per limb) within the spinal cord generate locomotor oscillations and control limb movements. Neural interactions between these generators define interlimb coordination and gait. Read More
    Mechanisms of left-right coordination in mammalian locomotor pattern generation circuits: a mathematical modeling view.
    PLoS Comput Biol 2015 May 13;11(5):e1004270. Epub 2015 May 13.
    Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, Pennsylvania, United States of America.
    The locomotor gait in limbed animals is defined by the left-right leg coordination and locomotor speed. Coordination between left and right neural activities in the spinal cord controlling left and right legs is provided by commissural interneurons (CINs). Several CIN types have been genetically identified, including the excitatory V3 and excitatory and inhibitory V0 types. Read More
    Organization of flexor-extensor interactions in the mammalian spinal cord: insights from computational modelling.
    J Physiol 2016 Nov 21;594(21):6117-6131. Epub 2016 Jul 21.
    Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA, USA.
    Key Points: Alternation of flexor and extensor activity in the mammalian spinal cord is mediated by two classes of genetically identified inhibitory interneurons, V1 and V2b. The V1 interneurons are essential for high-speed locomotor activity. They secure flexor-extensor alternations in the intact cord but lose this function after hemisection, suggesting that they are activated by inputs from the contralateral side of the cord. Read More
    Organization of the Mammalian Locomotor CPG: Review of Computational Model and Circuit Architectures Based on Genetically Identified Spinal Interneurons(1,2,3).
    eNeuro 2015 Sep 22;2(5). Epub 2015 Sep 22.
    Department of Neurobiology and Anatomy, Drexel University College of Medicine , Philadelphia, Pennsylvania 19129.
    The organization of neural circuits that form the locomotor central pattern generator (CPG) and provide flexor-extensor and left-right coordination of neuronal activity remains largely unknown. However, significant progress has been made in the molecular/genetic identification of several types of spinal interneurons, including V0 (V0D and V0V subtypes), V1, V2a, V2b, V3, and Shox2, among others. The possible functional roles of these interneurons can be suggested from changes in the locomotor pattern generated in mutant mice lacking particular neuron types. Read More