| Locomotion of vertebrates is generated under the coordination and control of Center Pattern Generator(CPG)located in the spinal cord.Its symbolic feature is that the neurons in the CPG generate periodic rhythmic signals and control the flexion and extension of skeletal muscles to make the limbs move.The rhythmic signal controlling limb movement is a pair of mutually inhibited and periodic electrophysiological signals.Its frequency,instantaneous frequency,peak value and other parameters play a very important role in analyzing the excitability of neurons and the speed and mode of movement.However,due to the complexity of the nervous system and the limitations of technical conditions,the mechanism of the regulation of CPG motor rhythm is still unclear.Physiological studies have shown that the generation of rhythmic signals is related to the connection mode of CPG,the endogenous characteristics of the neuron membrane that constitutes CPG,and the regulatory characteristics of neurotransmitters.A large number of studies have proved that ion channels play a very important role in regulating the endogenous characteristics of neuronal cell membrane,so it is very likely that ion channels also play an important role in the regulation of motor rhythm.Due to technical conditions,many problems cannot be completely studied through physiological experiments,so neural system modeling and simulation become an effective means to study such problems.In this paper,we will use the method of model simulation to study the regulatory effect of ion channels on the CPG motor rhythm.Based on the electrophysiological data of spinal motoneurons and interneurons in cats,a simplified spinal neural network model is constructed to generate motor rhythms.The network consists of mutually inhibited interneuron pools of flexor and extensor muscles,each containing 10 neurons.Each neuron is represented by a single compartment model embedded with six ion channels.In order to make the research results more statistically significant,the regulation of ion channels on the motor rhythm was deduced from the changes of the average frequency,average instantaneous frequency and average peak value of the motor rhythm.By adjusting the conductance of Persistent Sodium(Na P),Transient Sodium(Na T)and Calcium dependent Potassium(AHP)channels studied in this paper,the changes of motor rhythm were observed and analyzed.The main conclusions of the study are as follows:(1)The ion channels Na P,Na T and K(AHP)play an important role in regulating the motor rhythm,but each channel has different effects on regulating the parameters of the motor rhythm;(2)The regulation of a single ion channel can only have a significant effect on some parameters of the motor rhythm,while the regulation of multiple ion channels can have a significant effect on all parameters of the motor rhythm;(3)The generation of the rhythm signal shows the characteristics of "All or None";(4)Each parameter of the motor rhythm is sensitive to the direction of ion channel regulation.This paper studies the regulation of ion channels on CPG motor rhythm through neuron modeling and model simulation.The research results provide a basis for further neurophysiological experiments,and also provide a reference and idea for the design of intelligent motion control system. |
