Spontaneous And Induced Synaptic Activity Of Hippocampal CA1 Neurons In Awake Mice

The hippocampus is an important brain area for learning and memory.Present views hold that hippocampal processing of sensory information is an important part of hippocampal dependent learning and memory.Most researches of sensory information processing and memory in the hippocampus focus on the activity induced by spontaneous and sensory stimulation of hippocampal neurons,while the research methods mostly use the techniques such as extracellular electrophysiology and brain imaging.And further exploration of the spontaneous activity and induced activity of the hippocampus at subthreshold level has great significance to further reveal the neural mechanism of hippocampal function.Therefore,in this paper,we conducted a preliminary study on the synaptic activity of CA1 cone cells induced by spontaneous membrane potential activity and sound stimulation by using the whole-cell patch-clamp technique of head-fixed awake mice in the body combined with EEG monitoring.Spontaneous activity studies have found that the spontaneous activity of CA1 pyramidal cells changes significantly with the different states of EEG's active state and quiescent state.The mean membrane potential,resting membrane potential and action potential firing frequency of hippocampal CA1 pyramidal cells in Active state were significantly higher than those in the quiescent state.And the average membrane potential and action potential firing rate of spontaneous activity of hippocampal CA1 pyramidal cells in awake state were significantly lower than that in the state of anesthetic.The results of sound stimulation induced hippocampal CA1 pyramidal cell activity showed that pure tone stimulation can induce excitatory(about 28%),inhibitory(about 45%)or complex(about 10%)membrane potential response in CA1 pyramidal cells.And most of the pyramidal cells with membrane potential response are accompanied by action potential reactions.In addition,different stimulation intervals caused the evoked response amplitude to show different trends with the number of repetitions.The amplitude of the excitatory membrane potential response induced by the 6 s interval sound stimulation decreased with the increase of the number of stimulations.And in this state,there is no significant change in the amplitude of the inhibitory membrane potential response.The conclusions of this paper is: The spontaneous activity of hippocampal CA1 pyramidal cells in awake state has a corresponding relationship with EEG state,and the sound stimulation can induce the excitatory or inhibitory membrane potential and action potential of CA1 pyramidal cells.In this paper,we have conducted a synaptic level study on the spontaneous activity of hippocampal pyramidal cells and simple sensory information-inducing activities,which provide a further understanding for the hippocampal sensory information coding and learning memory.