Institute of Physiology, Department of Neurophysiology, University of Würzburg, 97070 Würzburg, Germany.
Cell Rep. 2013 May 30;3(5):1407-13. doi: 10.1016/j.celrep.2013.04.003. Epub 2013 May 2.
Synaptic plasticity shapes the development of functional neural circuits and provides a basis for cellular models of learning and memory. Hebbian plasticity describes an activity-dependent change in synaptic strength that is input-specific and depends on correlated pre- and postsynaptic activity. Although it is recognized that synaptic activity and synapse development are intimately linked, our mechanistic understanding of the coupling is far from complete. Using Channelrhodopsin-2 to evoke activity in vivo, we investigated synaptic plasticity at the glutamatergic Drosophila neuromuscular junction. Remarkably, correlated pre- and postsynaptic stimulation increased postsynaptic sensitivity by promoting synapse-specific recruitment of GluR-IIA-type glutamate receptor subunits into postsynaptic receptor fields. Conversely, GluR-IIA was rapidly removed from synapses whose activity failed to evoke substantial postsynaptic depolarization. Uniting these results with developmental GluR-IIA dynamics provides a comprehensive physiological concept of how Hebbian plasticity guides synaptic maturation and sparse transmitter release controls the stabilization of the molecular composition of individual synapses.
突触可塑性塑造了功能性神经回路的发育，并为学习和记忆的细胞模型提供了基础。赫布可塑性描述了一种依赖于活动的突触强度变化，这种变化具有输入特异性，并取决于前后突触活动的相关性。尽管人们认识到突触活动和突触发育是密切相关的，但我们对这种耦合的机制理解还远远不够。我们使用 Channelrhodopsin-2 在体内引发活动，研究了果蝇神经肌肉接头处的谷氨酸能突触可塑性。值得注意的是，前后突触的相关性刺激通过促进 GluR-IIA 型谷氨酸受体亚基在突触后受体场中的特异性募集，增加了突触后敏感性。相反，GluR-IIA 从那些未能引发明显突触去极化的突触中迅速被去除。将这些结果与发育中的 GluR-IIA 动力学结合起来，提供了一个全面的生理学概念，即赫布可塑性如何指导突触成熟，以及稀疏的递质释放如何控制单个突触的分子组成的稳定。
