Department of Biology, University of Ottawa, Ottawa, Ontario, K1N 6N5, Canada.
Center for Neural Dynamics, University of Ottawa, Ottawa, Ontario, K1N 6N5, Canada.
Sci Rep. 2020 Oct 7;10(1):16707. doi: 10.1038/s41598-020-73566-3.
The precise timing of neuronal activity is critical for normal brain function. In weakly electric fish, the medullary pacemaker network (PN) sets the timing for an oscillating electric organ discharge (EOD) used for electric sensing. This network is the most precise biological oscillator known, with sub-microsecond variation in oscillator period. The PN consists of two principle sets of neurons, pacemaker and relay cells, that are connected by gap junctions and normally fire in synchrony, one-to-one with each EOD cycle. However, the degree of gap junctional connectivity between these cells appears insufficient to provide the population averaging required for the observed temporal precision of the EOD. This has led to the hypothesis that individual cells themselves fire with high precision, but little is known about the oscillatory dynamics of these pacemaker cells. As a first step towards testing this hypothesis, we have developed a biophysical model of a pacemaker neuron action potential based on experimental recordings. We validated the model by comparing the changes in oscillatory dynamics produced by different experimental manipulations. Our results suggest that this relatively simple model can capture a large range of channel dynamics exhibited by pacemaker cells, and will thus provide a basis for future work on network synchrony and precision.
神经元活动的精确时间对于正常的大脑功能至关重要。在弱电鱼中，髓质起搏器网络 (PN) 为用于电感知的振荡电气器官放电 (EOD) 设置时间。这个网络是已知的最精确的生物振荡器，振荡器周期的变化小于微秒。PN 由两个主要的神经元组组成，起搏器和中继细胞，它们通过缝隙连接连接，通常与每个 EOD 周期一一同步发射。然而，这些细胞之间的缝隙连接连通性程度似乎不足以提供观察到的 EOD 时间精度所需的群体平均。这导致了一个假设，即单个细胞本身以高精度发射，但对于这些起搏器细胞的振荡动力学知之甚少。作为检验这一假设的第一步，我们根据实验记录开发了一个起搏器神经元动作电位的生物物理模型。我们通过比较不同实验操作产生的振荡动力学变化来验证模型。我们的结果表明，这个相对简单的模型可以捕捉到起搏器细胞表现出的大范围通道动力学，因此将为未来关于网络同步和精度的工作提供基础。
