The impact of short term synaptic depression and stochastic vesicle dynamics on neuronal variability.
The impact of short term synaptic depression and stochastic vesicle dynamics on neuronal variability.
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DOI：
10.1007/s10827-012-0438-0
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发表时间：
2013-08
影响因子：
1.2
通讯作者：
Rosenbaum R
中科院分区：
文献类型：
--
作者：
Reich S;Rosenbaum R
神经元的可变性在神经编码中起着核心作用，并影响神经网络的动力学。突触传递的不可靠性是神经变异性的一个主要来源：突触神经递质囊泡在突触前动作电位的响应下随机释放，并在时间上随机恢复。这一囊泡释放和恢复过程的动力学与突触前尖峰到达时间的可变性相互作用，形成突触后反应的可变性。我们使用连续时间马尔可夫链方法分析了一个具有随机囊泡动力学的短时突触抑制模型和三种不同的突触前放电模型：一种模型中突触前动作电位的时序被模拟为泊松过程，一种模型中动作电位的出现比泊松过程更规则(亚泊松)，另一种模型中动作电位的出现更不规则(超泊松)。我们使用这种分析来研究突触前棘波序列中的可变性是如何通过短期抑制和随机小泡动力学来确定突触后反应的可变性的。我们发现，亚泊松突触前尖峰放电增加了小泡释放的平均速率，在较小的时间窗内释放的小泡的数量比大的时间窗更具变异性，即使在突触前尖峰时间是非泊松的情况下，突触前快速尖峰放电也会引起突触后反应的泊松变异性。我们的结果补充和扩展了以前报道的理论结果，并为在记录数据中观察到的一些趋势提供了可能的解释。
Neuronal variability plays a central role in neural coding and impacts the dynamics of neuronal networks. Unreliability of synaptic transmission is a major source of neural variability: synaptic neurotransmitter vesicles are released probabilistically in response to presynaptic action potentials and are recovered stochastically in time. The dynamics of this process of vesicle release and recovery interacts with variability in the arrival times of presynaptic spikes to shape the variability of the postsynaptic response. We use continuous time Markov chain methods to analyze a model of short term synaptic depression with stochastic vesicle dynamics coupled with three different models of presynaptic spiking: one model in which the timing of presynaptic action potentials are modeled as a Poisson process, one in which action potentials occur more regularly than a Poisson process (sub-Poisson) and one in which action potentials occur more irregularly (super-Poisson). We use this analysis to investigate how variability in a presynaptic spike train is transformed by short term depression and stochastic vesicle dynamics to determine the variability of the postsynaptic response. We find that sub-Poisson presynaptic spiking increases the average rate at which vesicles are released, that the number of vesicles released over a time window is more variable for smaller time windows than larger time windows and that fast presynaptic spiking gives rise to Poisson-like variability of the postsynaptic response even when presynaptic spike times are non-Poisson. Our results complement and extend previously reported theoretical results and provide possible explanations for some trends observed in recorded data.