Department of Bioengineering, University of California, San Diego, La Jolla, 92093, CA, USA.
Center for Engineered Natural Intelligence, University of California, San Diego, La Jolla, 92093, CA, USA.
Sci Rep. 2018 Jul 11;8(1):10460. doi: 10.1038/s41598-018-28527-2.
Dynamic signaling on branching axons is critical for rapid and efficient communication between neurons in the brain. Efficient signaling in axon arbors depends on a trade-off between the time it takes action potentials to reach synaptic terminals (temporal cost) and the amount of cellular material associated with the wiring path length of the neuron's morphology (material cost). However, where the balance between structural and dynamical considerations for achieving signaling efficiency is, and the design principle that neurons optimize to preserve this balance, is still elusive. In this work, we introduce a novel analysis that compares morphology and signaling dynamics in axonal networks to address this open problem. We show that in Basket cell neurons the design principle being optimized is the ratio between the refractory period of the membrane, and action potential latencies between the initial segment and the synaptic terminals. Our results suggest that the convoluted paths taken by axons reflect a design compensation by the neuron to slow down signaling latencies in order to optimize this ratio. Deviations in this ratio may result in a breakdown of signaling efficiency in the cell. These results pave the way to new approaches for investigating more complex neurophysiological phenomena that involve considerations of neuronal structure-function relationships.
树突分支上的动态信号对于大脑中神经元之间的快速和有效通讯至关重要。轴突树突中有效的信号传递取决于动作电位到达突触末端所需的时间（时间成本）与神经元形态布线路径长度相关的细胞物质（物质成本）之间的权衡。然而，在实现信号效率的结构和动力学考虑之间的平衡点，以及神经元优化以保持这种平衡的设计原则，仍然难以捉摸。在这项工作中，我们引入了一种新的分析方法，比较了轴突网络中的形态和信号动力学，以解决这个悬而未决的问题。我们表明，在 Basket 细胞神经元中，被优化的设计原则是膜的不应期与初始段和突触末端之间的动作电位潜伏期之间的比例。我们的结果表明，轴突的曲折路径反映了神经元的一种设计补偿，即通过减缓信号传递延迟来优化这个比例。这种比例的偏差可能导致细胞信号效率的崩溃。这些结果为研究涉及神经元结构-功能关系的更复杂神经生理现象的新方法铺平了道路。
