Passive soma facilitates submillisecond coincidence detection in the owl's auditory system
Passive soma facilitates submillisecond coincidence detection in the owl's auditory system
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DOI：
10.1152/jn.00399.2006
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发表时间：
2007-03-01
影响因子：
2.5
通讯作者：
Konishi, Masakazu
中科院分区：
文献类型：
--
作者：
Ashida, Go;Abe, Kousuke;Konishi, Masakazu
鸟类的核层（NL）的神经元计算双耳时间差（ITD），通过检测符合到达双耳信号亚毫秒的精度。这种时间精度的细胞机制已经在理论和实验上研究了很长时间。在猫头鹰的NL神经元和小的听觉重合检测器神经元中观察到的各种动物的躯体尖峰的有髓轴突的初始段表明，在NL神经元的尖峰产生在第一节点的Ranvier和索马被动地接收反向传播的尖峰。为了研究“被动索马”结构的意义，我们构建了一个由细胞体和第一个节点组成的两室NL神经元模型，并系统地改变了每个室的兴奋性。在这里，我们表明，一个神经元与较不活跃的索马实现更高的ITD灵敏度和更高的噪声容忍度与较低的能量成本。我们还研究了生物物理机制的计算优势的“被动索马”结构进行子和阈上分析。设置具有高钠电导的锋电位起始位点，不在大索马中，而是在小节点中，用于放大高频输入信号并降低锋电位产生的影响和能量成本。我们的研究结果表明，猫头鹰的NL神经元使用“被动索马”的设计计算和代谢的原因。
Neurons of the avian nucleus laminaris (NL) compute the interaural time difference (ITD) by detecting coincident arrivals of binaural signals with submillisecond accuracy. The cellular mechanisms for this temporal precision have long been studied theoretically and experimentally. The myelinated axon initial segment in the owl's NL neuron and small somatic spikes observed in auditory coincidence detector neurons of various animals suggest that spikes in the NL neuron are generated at the first node of Ranvier and that the soma passively receives back-propagating spikes. To investigate the significance of the "passive soma" structure, we constructed a two-compartment NL neuron model, consisting of a cell body and a first node, and systematically changed the excitability of each compartment. Here, we show that a neuron with a less active soma achieves higher ITD sensitivity and higher noise tolerance with lower energy costs. We also investigate the biophysical mechanism of the computational advantage of the "passive soma" structure by performing sub- and suprathreshold analyses. Setting a spike initiation site with high sodium conductance, not in the large soma but in the small node, serves to amplify high-frequency input signals and to reduce the impact and the energy cost of spike generation. Our results indicate that the owl's NL neuron uses a "passive soma" design for computational and metabolic reasons.