The Functional Consequences of Changes in the Strength and Duration of Synaptic Inputs to Oscillatory Neurons
The Functional Consequences of Changes in the Strength and Duration of Synaptic Inputs to Oscillatory Neurons
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DOI：
10.1523/jneurosci.23-03-00943.2003
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发表时间：
2003-02
期刊：
影响因子：
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通讯作者：
A. Prinz;Vatsala Thirumalai;E. Marder
中科院分区：
文献类型：
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作者：
A. Prinz;Vatsala Thirumalai;E. Marder
通过在基于突触电导的起搏器模型中模拟突触电导脉冲，并用动态钳将人工突触电导脉冲注入龙虾胃胃神经节幽门起搏神经元，研究了不同幅度和持续时间的突触输入对神经振荡器的影响。在模型和生物神经元中，由增强强度饱和的抑制性和兴奋性输入引起的爆发期的变化，使得超过一定强度的突触输入对振荡神经元的放电模式都有相同的影响。相反，增加突触电导脉冲的持续时间总是会导致突触周期的变化，这表明神经振荡器对突触输入持续时间的变化很敏感，但对高于一定电导的突触输入强度的变化不敏感。这种对逐渐增强的突触输入的反应饱和不仅发生在爆裂型神经元中，也发生在紧张性尖峰神经元中。我们确定超极化电位下的内向电流是模型神经元饱和的原因。我们的发现表明，活动依赖或调节剂诱导的突触强度的变化并不一定伴随着突触对突触后尖峰或突触爆发的时间的功能影响的变化。
We studied the effect of synaptic inputs of different amplitude and duration on neural oscillators by simulating synaptic conductance pulses in a bursting conductance-based pacemaker model and by injecting artificial synaptic conductance pulses into pyloric pacemaker neurons of the lobster stomatogastric ganglion using the dynamic clamp. In the model and the biological neuron, the change in burst period caused by inhibitory and excitatory inputs of increasing strength saturated, such that synaptic inputs above a certain strength all had the same effect on the firing pattern of the oscillatory neuron. In contrast, increasing the duration of the synaptic conductance pulses always led to changes in the burst period, indicating that neural oscillators are sensitive to changes in the duration of synaptic input but are not sensitive to changes in the strength of synaptic inputs above a certain conductance. This saturation of the response to progressively stronger synaptic inputs occurs not only in bursting neurons but also in tonically spiking neurons. We identified inward currents at hyperpolarized potentials as the cause of the saturation in the model neuron. Our findings imply that activity-dependent or modulator-induced changes in synaptic strength are not necessarily accompanied by changes in the functional impact of a synapse on the timing of postsynaptic spikes or bursts.