The purpose of this study is to investigate the changes of synaptic efficacy in the rat hippocampal CA_3 region during establishment, extinction and re-establishment of conditioned drink response by means of implanted electrodes and behavioral observation. 本实验应用慢性埋植电极技术以电生理学结合行为学的方法,观察大鼠条件性饮水反应的建立、消退和再建立过程中,其海马CA3区突触效应的变化规律。