Simulation of Primary Afferent Synapses in Unmyelinated Nerve Fiber

The primary C-fiber afferent synapses is a glutamatergic synapse in the sensory pathway designed to transfer the chronic and dull pain information. Electrophysiological recordings from this synapse reveal some forms of facilitation and depression. To investigate the modulation mechanisms of synaptic transmission at primary C-fiber afferent synapse,we have developed a computational model which include pre- and postsynaptic components. The presynaptic component modified Hodgkin-Huxley equations to simulate the ionic and electrical events in a small unmyelinated nerve fiber terminal. Postsynaptic component include AMPA and NMDA receptors kinetics. The behaviour of the model is compared to experimental data and reproduce amplitude of synaptic depression during repetitive and bursting stimulation at different frequencies.The model shows steady-state depressions are frequencies related. Simulation of a single synaptic demonstrate the synapses depress during presynaptic stimulation due to depletion of presynaptic vesicles mainly.