THE DYNAMICS OF FREE CALCIUM IN DENDRITIC SPINES IN RESPONSE TO REPETITIVE SYNAPTIC INPUT
THE DYNAMICS OF FREE CALCIUM IN DENDRITIC SPINES IN RESPONSE TO REPETITIVE SYNAPTIC INPUT
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DOI：
10.1126/science.3495885
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发表时间：
1987-06-05
期刊：
影响因子：
56.9
通讯作者：
KOCH, C
中科院分区：
文献类型：
--
作者：
GAMBLE, E;KOCH, C
突触前或突触后细胞内钙水平的升高被认为是突触强度变化的前兆。因此，为了诱导海马体的长期增强，强烈的突触刺激周期必须短暂地提高突触后部位（大多数情况下是树突棘）的胞质钙水平。由于目前不可能直接实验验证这一假设，因此通过数值求解两种不同突触后结构的适当电扩散方程来研究钙水平。假设电压依赖性钙通道存在于树突棘上，假设电压依赖性钙通道存在于树突棘上，那么在20毫秒内，仅需7次峰后，棘中的游离细胞内钙就可以达到微摩尔水平。此外，短而高频的突触前活动爆发比持续的低频活动更有效地提高钙水平，特别是钙-钙调蛋白复合物的水平。这种行为不同于在典型脊椎动物神经元的胞体上看到的行为。
Increased levels of intracellular calcium at either pre- or postsynaptic sites are thought to precede changes in synaptic strength. Thus, to induce long-term potentiation in the hippocampus, periods of intense synaptic stimulation would have to transiently raise the levels of cytosolic calcium at postsynaptic sites-dendritic spines in the majority of cases. Since direct experimental verification of this hypothesis is not possible at present, calcium levels have been studied by numerically solving the appropriate electro-diffusion equations for two different postsynaptic structures. Under the assumption that voltage-dependent calcium channels are present on dendritic spines, assumption that voltage-dependent calcium channels are present on dendritic spines, free intracellular calcium in spines can reach micromolar levels after as few as seven spikes in 20 milliseconds. Moreover, a short, but high-frequency, burst of presynaptic activity is more effective in raising levels of calcium and especially of the calcium-calmodulin complex than sustained low-frequency activity. This behavior is different from that seen at the soma of a typical vertebrate neuron.