Wahl L M, Stratford K J, Larkman A U, Jack J J
University Laboratory of Physiology, Oxford, U.K.
Proc Biol Sci. 1995 Oct 23;262(1363):77-85. doi: 10.1098/rspb.1995.0179.
Variability in the measured amplitude of evoked synaptic events can arise from several factors, including: measurement noise, trial-to-trial variation in the amplitude of the response at a single release site, or variation between different release sites (inter-site variation) in the mean amplitude of the single quantal response. Classic (linear) models of variability include only the first two of these factors, although differences in the number of postsynaptic receptors or the degree of electrotonic attenuation for different release sites could cause substantial inter-site variations in quantal size. In this paper, the effect of inter-site variation on the variance of successive histogram peaks has been determined analytically and verified by computational studies. This effect is minimal at the edges of the histogram and contributes maximally to central peaks. Linear approximations to the variance of successive histogram peaks may therefore result in very poor fits to measured data if substantial inter-site variation in quantal size is involved. Our computational results indicate that for synaptic contacts with high release probabilities and substantial inter-site variation, the variance of histogram peaks will decrease with increasing quantal content.
诱发突触事件测量幅度的变异性可能源于几个因素，包括：测量噪声、单个释放位点处反应幅度的逐次试验变化，或不同释放位点之间（位点间变化）单个量子反应平均幅度的变化。经典（线性）变异性模型仅包括前两个因素，尽管不同释放位点的突触后受体数量差异或电紧张衰减程度可能导致量子大小出现显著的位点间变化。在本文中，已通过分析确定了位点间变化对连续直方图峰值方差的影响，并通过计算研究进行了验证。这种影响在直方图边缘处最小，对中心峰值的贡献最大。因此，如果量子大小存在显著的位点间变化，连续直方图峰值方差的线性近似可能导致与测量数据的拟合非常差。我们的计算结果表明，对于具有高释放概率和显著位点间变化的突触接触，直方图峰值的方差将随着量子含量的增加而减小。
