Isaac J T, Hjelmstad G O, Nicoll R A, Malenka R C
Department of Psychiatry, University of California, San Francisco 94143, USA.
Proc Natl Acad Sci U S A. 1996 Aug 6;93(16):8710-5. doi: 10.1073/pnas.93.16.8710.
Despite extensive investigation, it remains unclear whether presynaptic and/or postsynaptic modifications are primarily responsible for the expression of long-term potentiation (LTP) in the CA1 region of the hippocampus. Here we address this issue by using techniques that maximize the likelihood of stimulating a single axon and thereby presumably a single synapse before and after the induction of LTP. Several basic properties of synaptic transmission were examined including the probability of neurotransmitter release (Pr), the quantal size (q), and the so-called potency, which is defined as the average size of the synaptic response when release of transmitter does occur. LTP was routinely associated with an increase in potency, whereas increases in Pr alone were not observed. LTP was also reliably induced when baseline Pr was high, indicating that synapses with high Pr can express LTP. These results suggest that the mechanism for the expression of LTP involves an increase in q and is difficult to explain by an increase in Pr alone.
尽管进行了广泛的研究，但尚不清楚突触前和/或突触后修饰是否主要负责海马体CA1区长期增强（LTP）的表达。在这里，我们通过使用一些技术来解决这个问题，这些技术能最大程度地提高在诱导LTP前后刺激单个轴突以及由此推测刺激单个突触的可能性。我们检查了突触传递的几个基本特性，包括神经递质释放概率（Pr）、量子大小（q）以及所谓的效能，效能定义为递质释放时突触反应的平均大小。LTP通常与效能增加相关，而单独的Pr增加未被观察到。当基线Pr较高时，LTP也能可靠地诱导产生，这表明具有高Pr的突触可以表达LTP。这些结果表明，LTP表达的机制涉及q的增加，仅靠Pr的增加难以解释。
