Institut für Physik, Humboldt-Universität zu Berlin, Berlin, Germany.
Universidade Federal do ABC, Santo André, SP, Brazil.
PLoS Comput Biol. 2019 Apr 29;15(4):e1006355. doi: 10.1371/journal.pcbi.1006355. eCollection 2019 Apr.
Spontaneous waves in the developing retina are essential in the formation of the retinotopic mapping in the visual system. From experiments in rabbits, it is known that the earliest type of retinal waves (stage I) is nucleated spontaneously, propagates at a speed of 451±91 μm/sec and relies on gap junction coupling between ganglion cells. Because gap junctions (electrical synapses) have short integration times, it has been argued that they cannot set the low speed of stage I retinal waves. Here, we present a theoretical study of a two-dimensional neural network of the ganglion cell layer with gap junction coupling and intrinsic noise. We demonstrate that this model can explain observed nucleation rates as well as the comparatively slow propagation speed of the waves. From the interaction between two coupled neurons, we estimate the wave speed in the model network. Furthermore, using simulations of small networks of neurons (N≤260), we estimate the nucleation rate in the form of an Arrhenius escape rate. These results allow for informed simulations of a realistically sized network, yielding values of the gap junction coupling and the intrinsic noise level that are in a physiologically plausible range.
发育中的视网膜中的自发波对于视觉系统中视域映射的形成至关重要。从对兔子的实验中可知，最早的视网膜波类型（I 期）是自发产生的，传播速度为 451±91 μm/sec，依赖于神经节细胞之间的缝隙连接耦合。由于缝隙连接（电突触）具有较短的整合时间，因此有人认为它们不能设定 I 期视网膜波的低速。在这里，我们提出了一个具有缝隙连接耦合和固有噪声的二维神经节细胞层的理论研究。我们证明，该模型可以解释观察到的成核率以及波的相对较慢的传播速度。从两个耦合神经元的相互作用中，我们估计了模型网络中的波速。此外，通过对小神经元网络（N≤260）的模拟，我们以 Arrhenius 逃逸率的形式估计了成核率。这些结果允许对真实大小的网络进行信息丰富的模拟，从而产生具有生理上合理范围的缝隙连接耦合和固有噪声水平的值。
