Numerical Study Of Random Hodgkin-huxley Neuronal Synaptic Inhibition And Theta-nested Gamma Coupled Oscillations

The response of a postsynaptic neuron is related to the form of synaptic input.The release of neurotransmitters from vesicles in each presynaptic neuron causes the exciation or inhibition in a postsynaptic neuron.This thesis studies the response of a postsynaptic neuron to presynatic inhibition,and the phase amplitude coupling which produce theta-nested gamma oscillations in a random Hodgkin-Huxley neuonal networkIn the first part,presented a probabilistic model describing the synaptic release of ex-citatory neurons.Two different types of synaptic connections are used:(i)N presynaptic neurons are connected to one postsynaptic neuron;(ii)a presynaptic neuron is connected to a postsynaptic neuron.The stability of postsynaptic response and the probability distribution of its current are discussed by numerical simulation.With the increase of disturbance coefficient D,the response of postsynaptic neurons is more and more unsta-ble.Postsynaptic current obeys a normal distribution even if the synaptic connections are different.In the second part,consider a the random Hodgkin-Huxley neuron model by using the synaptic structure of N presynaptic neurons and one postsynaptic neuron.It is show that synaptic inhibition is can produce different postsynaptic responses.Under the action of synaptic inhibition(?D>?F,the sensitivity of postsynaptic neurons to the low presynaptic frequency input is enhanced.thus,I also show that synaptic inhibition is crucial for controlling the balance between neuronal excitation and inhibitionIn the third part,a neural network model is introduced.The network consists of three kinds of neurons:excitatory neurons,fast inhibitory neurons and slow inhibitory neurons,which can produce in the form of theta-nested gamma oscillations.Among them,GABA receptor is the most important factor to produce this oscillation regulation GABA receptor can be divided into two types:GABAfast and GABAslow.Current studies have shown that GABAslow receptor can regulate the generation of theta rhythm,while GABAfast receptor can regulate the generation of gamma rhythm.When the phase of the theta rhythm oscillation regulates the amplitude of the gamma rhythm oscillation,theta-nested gamma oscillations are generated.Therefore,in order to produce the phase-amplitude coupling oscillation,the synaptic connections between fast inhibitory neurons,slow inhibitory neurons and excitatory neurons are needed.The following research is carried out by using this model:(i)effects of inhibitory neuronal synaptic connections(?GAsf,?GAff,?GAss)on theta-nested gamma oscillations;(ii)effects of excitatory neu-ronal synaptic connections(?NMee,?NMef,?NMes)on theta-nested gamma oscillations(iii)the generation of coupling oscillations of theta-nested gamma under different cell membrane areas.When the cell membrane area S=100?m2,more spontaneous firings occur in neurons in the form of theta-nested gamma oscillations under the influence of channel noise.When the cell membrane area S=300 ?m2,the influence of channel noise is reduced and the spontaneous firings of neurons are significantly reduced,so the theta-nested gamma oscillations are also reduced.When the cell membrane area S=500 ?m2,the neurons hardly fire,so no theta-nested gamma oscillations occur.