Du Jiu-Lin, Poo Mu-Ming
Division of Neurobiology, Department of Molecular and Cell Biology, Helen Wills Neuroscience Institute, University of California, Berkeley, California 94720, USA.
Nature. 2004 Jun 24;429(6994):878-83. doi: 10.1038/nature02618.
In cultures of hippocampal neurons, induction of long-term synaptic potentiation or depression by repetitive synaptic activity is accompanied by a retrograde spread of potentiation or depression, respectively, from the site of induction at the axonal outputs to the input synapses on the dendrites of the presynaptic neuron. We report here that rapid retrograde synaptic modification also exists in an intact developing retinotectal system. Local application of brain-derived neurotrophic factor (BDNF) to the Xenopus laevis optic tectum, which induced persistent potentiation of retinotectal synapses, led to a rapid modification of synaptic inputs at the dendrites of retinal ganglion cells (RGCs), as shown by a persistent enhancement of light-evoked excitatory synaptic currents and spiking activity of RGCs. This retrograde effect required TrkB receptor activation, phospholipase Cgamma activity and Ca2+ elevation in RGCs, and was accounted for by a selective increase in the number of postsynaptic AMPA-subtype glutamate receptors at RGC dendrites. Such retrograde information flow in the neuron allows rapid regulation of synaptic inputs at the dendrite in accordance to signals received at axon terminals, a process reminiscent of back-propagation algorithm for learning in neural networks.
在海马神经元培养物中，重复性突触活动诱导长期突触增强或抑制时，分别伴随着增强或抑制从轴突输出端的诱导位点向突触前神经元树突上的输入突触逆行传播。我们在此报告，在完整的发育中的视网膜顶盖系统中也存在快速逆行突触修饰。将脑源性神经营养因子（BDNF）局部应用于非洲爪蟾的视顶盖，可诱导视网膜顶盖突触的持续增强，这导致视网膜神经节细胞（RGCs）树突处的突触输入快速修饰，表现为RGCs光诱发兴奋性突触电流和放电活动的持续增强。这种逆行效应需要RGCs中的TrkB受体激活、磷脂酶Cγ活性和Ca2+升高，并且是由RGCs树突处突触后AMPA亚型谷氨酸受体数量的选择性增加所导致的。神经元中的这种逆行信息流允许根据轴突终末接收到的信号快速调节树突处的突触输入，这一过程让人联想到神经网络学习中的反向传播算法。
