Sergey N. Markin

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The brainstem respiratory network can operate in multiple functional states engaging different state-dependent neural mechanisms. These mechanisms were studied in the in situ perfused rat brainstem-spinal cord preparation using sequential brainstem transections and administration of riluzole, a pharmacological blocker of persistent sodium current (INaP).(More)
A simple neuromechanical model has been developed that describes a spinal central pattern generator (CPG) controlling the locomotor movement of a single-joint limb via activation of two antagonist (flexor and extensor) muscles. The limb performs rhythmic movements under control of the muscular, gravitational and ground reaction forces. Muscle afferents(More)
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(More)
We have developed a computational model of the spinal cord neural circuitry that controls locomotor movements of simulated cat hindlimbs. The neural circuitry includes two central pattern generators integrated with re4ex circuits. All neurons were modeled in the Hodgkin– Huxley style. The musculoskeletal system includes two three-joint hindlimbs and the(More)
We compared the activity profiles and synergies of spinal motoneurons recorded during fictive locomotion evoked in immobilized decerebrate cat preparations by midbrain stimulation to the activity profiles and synergies of the corresponding hindlimb muscles obtained during forward level walking in cats. The fictive locomotion data were collected in the(More)
Locomotion in mammals is controlled by a spinal central pattern generator (CPG) coupled to a biomechanical limb system, with afferent feedback to the spinal circuits and CPG closing the control loop. We have considered a simplified model of this system, in which the CPG establishes a rhythm when a supra-spinal activating drive is present and afferent(More)
In this paper we analyze a closed loop neuromechanical model of locomotor rhythm generation. The model is composed of a spinal central pattern generator (CPG) and a single-joint limb, with CPG outputs projecting via motoneurons to muscles that control the limb and afferent signals from the muscles feeding back to the CPG. In a preceding companion paper(More)
Simulation of biologically plausible neural models from a single cell to networks usually requires substantial computational resources for numerical solution of differential equations. Various advanced methods to reduce the computational cost but keep an accuracy and effectiveness of solving differential equations are offered and implemented in several(More)
We have developed a neuromechanical computational model of cat hindlimb locomotion controlled by spinal central pattern generators (CPGs, one per hindlimb) and motion-dependent afferent feedback. Each CPG represents an extension of previously developed two-level model (Rybak et al. J Physiol 577:617–639, 2006a, J Physiol 577:641–658, 2006b) and includes a(More)
Existing models have represented a locomotor system as a rhythmic driver, or central pattern generator (CPG), coupled to a mechanical limb, with feedback closing the loop. Our collaborators have developed a version of this model in which the CPG establishes a rhythm when activating drive is present, and feedback from ground strike helps control phase(More)