Investigation Of The Neuronal Circuit Response To Electrical Stimulation In Hippocampus

The neuronal circuit of the hippocampus in our brain comprises excitatory and inhibitory synapses, which is related with learning, memory and other high functions in central nervous system. Besides, electrical stimulation has been applied clinically to treat brain disease, such as Parkinson's disease. Therefore, it is of great significance that investigation on the mechanism of excitatory and inhibitory circuit response to electrical stimulation in hippocampus. It could help revealing the mechanism of advanced information-processing capabilities of brain and developing new treatments of brain diseases.In this paper, two models were presented to simulate paired-pulse depression (PPD) of evoked population spike (PS) and evoked bursts after adding inhibitory synaptic antagonist. One is simple circuit with one pyramidal cell in CA1 and the other is microcircuit with 100 pyramidal cells. In addition, simple circuit model was used to simulate somatic activities driven by high frequency stimulation (HFS).And compared with electrophysiological experimental data, the following results were observed:(1) The simulation of two models verified results of experiment in vivo that, PPD could be recorded only in Orthodromic-Orthodromic (OO) and Antidromic-Orthodromic (AO) protocol. And the ratio of PPD varyied by inter-pulse interval (IPI).Thus, the effective duration of IPI was presented and the maximum value of the duration was proportion to the decay parameter of GABAA, and the minimum value of the duration had nothing to do with any parameters of GABAA.(2) During the simulation of simple circuit, it was found that the inhibitory synapses at proximal apical dendrites and soma played a major role in inhibitory circuits.(3) It was observed in vivo that adding the inhibitory antagonist induced a period of primary burst followed by secondary burst. It could be confirmed by models that the duration of primary burst was proportional to the decay parameters of AMPA and the number of secondary bursts was proportional to delay time (4) The parameter corresponding GABAA, AMPA and NMDA could be determined by effective duration of IPI, the duration of primary burst and number of secondary bursts respectively. In a word, results show that synapses on proximal apical and soma of pyramidal cell play the main role in PPD of PS. AMPA and NMDA are vital factors to induce the primary and secondary burst respectively. Besides, in this paper, a new method is presented to determine the corresponding parameters of receptor.