active hippocampal networks undergo spontaneous synaptic modification活跃的海马突触修改网络进行自发的.pdfVIP

Active Hippocampal Networks Undergo Spontaneous Synaptic Modification 1 1 1 1 1 1 2 Masako Tsukamoto-Yasui , Takuya Sasaki , Wataru Matsumoto , Ayako Hasegawa , Takeshi Toyoda , Atsushi Usami , Yuichi Kubota , Taku 2 2 1 1,3 Ochiai , Tomokatsu Hori , Norio Matsuki , Yuji Ikegaya * 1 Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan, 2 Department of Neurosurgery, Tokyo Women’s Medical University, Shinjuku-ku, Tokyo, Japan, 3 Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Agency, Tokyo, Japan The brain is self-writable; as the brain voluntarily adapts itself to a changing environment, the neural circuitry rearranges its functional connectivity by referring to its own activity. How the internal activity modifies synaptic weights is largely unknown, however. Here we report that spontaneous activity causes complex reorganization of synaptic connectivity without any external (or artificial) stimuli. Under physiologically relevant ionic conditions, CA3 pyramidal cells in hippocampal slices displayed spontaneous spikes with bistable slow oscillations of membrane potential, alternating between the so-called UP and DOWN states. The generation of slow oscillations did not require fast synaptic transmission, but their patterns were coordinated by local circuit activity. In the course of generating spontaneous activity, individual neurons acquired bidirectional long-lasting synaptic modification. The spontaneous synaptic plasticity depended on a rise in intracellular calcium concentrations of