Neurowissenschaftliches Forschungszentrum, Charité-Universitätsmedizin Berlin, 10117 Berlin, Germany.
Neuron. 2011 Oct 6;72(1):137-52. doi: 10.1016/j.neuron.2011.08.016.
High-frequency hippocampal network oscillations, or "ripples," are thought to be involved in episodic memory. According to current theories, memory traces are represented by assemblies of principal neurons that are activated during ripple-associated network states. Here we performed in vivo and in vitro experiments to investigate the synaptic mechanisms during ripples. We discovered postsynaptic currents that are phase-locked to ripples and coherent among even distant CA1 pyramidal neurons. These fast currents are consistent with excitatory postsynaptic currents (EPSCs) as they are observed at the equilibrium potential of Cl(-), and they display kinetics characteristic of EPSCs. Furthermore, they survived after intracellular blockade of GABAergic transmission and are effective to regulate the timing of action potentials. In addition, our data show a progressive synchronization of phasic excitation and inhibition during the course of ripples. Together, our results demonstrate the presence of phasic excitation during ripples reflecting an exquisite temporal coordination of assemblies of active pyramidal cells.
高频海马网络振荡，或“涟漪”，被认为与情景记忆有关。根据目前的理论，记忆痕迹由在与涟漪相关的网络状态期间被激活的主神经元集合来表示。在这里，我们进行了体内和体外实验来研究涟漪期间的突触机制。我们发现与涟漪锁相并且在即使是遥远的 CA1 锥体神经元之间也具有相干性的突触后电流。这些快速电流与兴奋性突触后电流 (EPSC) 一致，因为它们在 Cl(-) 的平衡电位下被观察到，并且它们表现出与 EPSC 特征一致的动力学特性。此外，它们在 GABA 能传递的细胞内阻断后仍然存在，并且能够有效地调节动作电位的时间。此外，我们的数据显示在涟漪过程中相位兴奋和抑制的逐渐同步。总之，我们的结果表明在涟漪期间存在相兴奋，反映了活跃的锥体细胞集合的精确时间协调。
