Abstract
Motoneuron is the control unit of skeletal muscles, and the dynamic frequency-regulating feedback from the afferent nerve of receptors like muscle spindles forms the physical basis of its closed-loop regulation. Focused on the synapses of muscle spindle afferents, this paper established a dynamical system-Markov model starting from presynaptic stimulations to postsynaptic responses, and further verified the model via comparisons between theoretical results and relevant experimental data. With the purpose of describing the active features of dendritic membrane, we employed the methods of dynamical systems rather than the traditional passive cable theory, and identified the physical meaning of parameters involved. For the dynamic behavior of postsynaptic currents, we adopted simplified Markov models so that the analytical solutions for the open dynamics of postsynaptic receptors can be obtained. The model in this paper is capable of simulating the actual non-uniformity of channel density, and is suitable for complex finite element analysis of neurons; thus it facilitates the exploration of the frequency-regulating feedback and control mechanisms of motoneurons.
Highlights
Motoneuron is the control unit of skeletal muscles, and the dynamic frequency-regulating feedback from the afferent nerve of receptors like muscle spindles forms the physical basis of its closed-loop regulation
We have proposed the bioelectrochemical frequency-regulating control mechanism for skeletal muscle based on the characteristics of the action potential (AP) on muscle fibers [4], i.e. the working process of muscle is regulated by the frequency of AP in real time
Thereby, the modeling method we proposed can be applied in the finite element analysis of motoneurons, and the disadvantage of the electrical model which cannot reflect the detailed features of the membrane can be overcome
Summary
Ionotropic receptors can be classified into two categories according to the types of transmitter that they receive [7]: one category is called N-methyl-D-aspartate (NMDA) receptor, i.e. this kind of receptors bind with NMDA-type transmitter to open, and the other class is non-NMDA receptor. These two types of receptors coexist in the synapses of motoneurons; the excitatory postsynaptic current during rapid signaling is the superposition of their respective currents. We see that for chemical synapses, there always exists a cycle in which presynaptic potential induces postsynaptic current, which is transferred into presynaptic potential again, and it is necessary to build a dynamic model for membrane potential first
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