Simulation And Implementation Of Biological Synapse Based On FPGA

In the biological nervous system,neurons are interconnected by synapses.The transmission function of synapses mainly lies in the communication of information between neurons.The transmission process is complicated and the dominant transmission method is chemical synaptic transmission.In this thesis,the main research object was to study the excitatory chemical synapse.Hodgkin-Huxley model,which was used to describe the action potential generation and conduction mechanism of neurons,was used as the pre-synaptic and post-synaptic neurons.The chemical synapse model based on different mechanisms was connected double HH neuron models constitute a simple chemical synaptic unidirectional coupling structure.Five kinds of chemical synapse models were modeled,simulated and implemented by hardware.Firstly,the basic theory and mathematical model of biological neurons and synapses were introduced.The basic structure of neurons and synapses was described,and the electrophysiological activities of neurons and electrophysiological characteristics of synapses were described.The mathematical model of neurons,that is,HH neuron model and five different mathematical models of chemical synapses were described.Secondly,the numerical simulation of neuronal synapses was investigated.Simulink modeling and simulation of five chemical synapse models based on different mechanisms were conducted to investigate the chemical synaptic transmission characteristics and the correlation coefficient method was used to compare the simulation results of five chemical synapses.The most biological model of five chemical synapse models was analyzed.In addition,one of the chemical synapse models for the study,the analysis of the synaptic neurotransmitter concentration and coupling strength of different factors on the synaptic response and postsynaptic neuronal activity.The results showed that in the synaptic cleft neurotransmitter concentration and coupling strength were small,the post-synaptic neuronal activity was to generate excitatory post-synaptic potential,when the synaptic cleft neurotransmitter concentration and coupling strength were large,post-synaptic neuronal activity was the production of action potential,and as the synaptic cleft neurotransmitter concentration and coupling strength increased,the post-synaptic neuronal action potential rose rapidly.Finally,chemical synapses were implemented by hardware.Five kinds of chemical synapse model were implemented by using Field Programmable Gate Array(FPGA)and DSP Builder.The same current stimulation was applied to presynaptic neurons in five chemical synapse models,and the hardware results of five chemical synapses were obtained.And the hardware results well reproduced the transmission characteristics of chemical synapses.The results were compared with the simulation results to verify the correctness of the hardware results of the biological chemical synapse model.