Engert F, Bonhoeffer T
Max Planck Institute for Psychiatry, München-Martinsried, Germany.
Nature. 1997 Jul 17;388(6639):279-84. doi: 10.1038/40870.
Long-term potentiation (LTP), the long-lasting increase in synaptic transmission, has been proposed to be a cellular mechanism essential for learning and memory, neuronal development, and circuit reorganization. In the original theoretical and experimental work it was assumed that only synapses that had experienced concurrent pre- and postsynaptic activity are subject to synaptic modification. It has since been shown, however, that LTP is also expressed in synapses on neighbouring neurons that have not undergone the induction procedure. Yet, it is still believed that this spread of LTP is limited to adjacent postsynaptic cells, and does not occur for synapses on neighbouring input fibres. However, for technical reasons, tests for 'input specificity' were always done for synapses relatively far apart. Here we have used a new local superfusion technique, which allowed us to assess the synaptic specificity of LTP with a spatial resolution of approximately 30 microm. Our results indicate that there is no input specificity at a distance of less than 70 microm. Synapses in close proximity to a site of potentiation are also potentiated regardless of their own history of activation, whereas synapses far away show no potentiation.
长期增强作用（LTP），即突触传递的持久增强，被认为是学习与记忆、神经元发育以及神经回路重组所必需的一种细胞机制。在最初的理论和实验工作中，人们假定只有经历了突触前和突触后同时活动的突触才会发生突触修饰。然而，后来的研究表明，LTP也在未经过诱导程序的相邻神经元的突触中表达。然而，人们仍然认为这种LTP的传播仅限于相邻的突触后细胞，而不会发生在相邻输入纤维上的突触。然而，由于技术原因，“输入特异性”测试总是针对相距较远的突触进行的。在这里，我们使用了一种新的局部灌注技术，它使我们能够以大约30微米的空间分辨率评估LTP的突触特异性。我们的结果表明，在小于70微米的距离内不存在输入特异性。靠近增强位点的突触也会被增强，无论它们自身的激活历史如何，而远处的突触则没有增强。
