Wilson C J
J Neurosci. 1984 Jan;4(1):281-97. doi: 10.1523/JNEUROSCI.04-01-00281.1984.
A cable model of the linear properties of dendritic spines was generated using the Laplace transform technique. Analytical solutions for the voltages generated in the spine by a current impulse at the spine head were used in a numerical procedure for simulating the effect of a synaptic conductance change. The synaptic current produced by the conductance change was used as an input for evaluation of the postsynaptic potential and current injected into the dendrite at the base of the spine. The primary effect of the dendritic spine was to attenuate synaptic current. This effect was produced by the high input impedance at axospinous synapses, which resulted in giant spike-like excitatory postsynaptic potentials (EPSPs) that approached the reversal potential of the synapse and thus reduced the potential gradient driving the synaptic current. Although virtually all of the synaptic current was transferred to the dendrite, it produced much smaller EPSPs there due to the low dendritic input impedance. Very small conductance changes produced near maximal synaptic currents in dendritic spines. The current attenuating effect of the spine was accentuated with brief synaptic transients and reduced with prolonged synaptic conductance changes. The size and shape of the spine head, and the diameter and boundary conditions of the dendrite had little or no effect on current attenuation for spines in the naturally occurring size range. The diameter and length of the spine stalk and the size and location of the spine apparatus were the key morphological factors determining the synaptic currents generated by axospinous synapses. Naturally occurring size and shape differences among dendritic spines produced large differences in synaptic potency when compared in a model spiny neuron based on the neostriatal spiny projection neuron. These differences were comparable to those produced by differences in synaptic-location on the same neuron.
利用拉普拉斯变换技术生成了树突棘线性特性的电缆模型。通过数值程序，使用棘突头部电流脉冲在棘突中产生的电压解析解来模拟突触电导变化的影响。电导变化产生的突触电流被用作评估突触后电位和注入棘突基部树突的电流的输入。树突棘的主要作用是衰减突触电流。这种作用是由轴棘突触处的高输入阻抗产生的，这导致了接近突触反转电位的巨大尖峰状兴奋性突触后电位（EPSP），从而降低了驱动突触电流的电位梯度。尽管几乎所有的突触电流都转移到了树突，但由于树突的低输入阻抗，在那里产生的EPSP要小得多。在树突棘中，非常小的电导变化产生于接近最大突触电流处。棘突的电流衰减作用在短暂的突触瞬变时增强，在突触电导长时间变化时减弱。在自然大小范围内，棘突头部的大小和形状以及树突的直径和边界条件对电流衰减几乎没有影响。棘突柄的直径和长度以及棘器的大小和位置是决定轴棘突触产生的突触电流的关键形态学因素。与基于新纹状体棘状投射神经元的模型棘状神经元相比，树突棘之间自然存在的大小和形状差异在突触效能上产生了很大差异。这些差异与同一神经元上突触位置差异产生的差异相当。
