Hayashida Yuki, Kudo Yuka, Ishida Ryoya, Okuno Hirotsugu, Yagi Tetsuya
Graduate School of Engineering, Osaka University, Suita, Japan.
IEEE Trans Biomed Circuits Syst. 2017 Jun;11(3):597-611. doi: 10.1109/TBCAS.2017.2662659. Epub 2017 May 19.
To gain insights on how visual information of the real world is filtered, compressed, and encoded by the vertebrate retinas, emulating in silico the spatiotemporal patterns of the graded and action potentials of neuronal responses to natural visual scenes on biological time scale is a feasible approach. As a basic platform for such an emulation, we here developed a compact hardware system comprising an analog silicon retina and a field-programmable gate array module. With utilizing the Izhikevich formalism, a retinal circuit model that emulates spiking of ganglion cells was implemented in this system. The emulated spike timing had the resolution of about 2 ms relative to the stimulus onset and was little affected by timings of the synchronous frame sampling in the silicon retina. Thus, the emulator can mimic the event-driven spike outputs of biological retinas. The system was useful for simultaneously visualizing neural images of both the graded potentials and the spikes in response to real live visual scenes. Since our emulator system is reconfigurable, it provides a flexible platform for investigating visual functions of retinal circuits under natural visual environment.
为了深入了解脊椎动物视网膜如何对现实世界的视觉信息进行过滤、压缩和编码，在生物时间尺度上通过计算机模拟神经元对自然视觉场景反应的分级电位和动作电位的时空模式是一种可行的方法。作为这种模拟的一个基本平台，我们在此开发了一个紧凑的硬件系统，该系统包括一个模拟硅视网膜和一个现场可编程门阵列模块。利用伊日克维奇形式体系，在该系统中实现了一个模拟神经节细胞放电的视网膜电路模型。模拟的尖峰时间相对于刺激开始具有约2毫秒的分辨率，并且几乎不受硅视网膜中同步帧采样时间的影响。因此，该模拟器可以模拟生物视网膜的事件驱动尖峰输出。该系统可用于同时可视化响应真实视觉场景的分级电位和尖峰的神经图像。由于我们的模拟器系统是可重新配置的，它为在自然视觉环境下研究视网膜电路的视觉功能提供了一个灵活的平台。
