A mathematical model of the retina based on neurophysiological mechanisms

基于神经生理机制的视网膜数学模型

基本信息

批准号：
17500195
负责人：
KAMIYAMA Yoshimi
金额：
$ 2.39万
依托单位：
Aichi Prefectural University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2007
项目状态：
已结题

项目摘要

The vertebrate retina has been thought to be a window to the brain because of its accessibility and suitability for neuroscientific investigation. It is thought to be one of the few parts of the vertebrate brain where we can reasonably explain its purpose and how it works. The retina is an ideal model of an information processing neural network, describing how neurons interact to codify and process visual information. Over the last decade, we have developed mathematical models of retinal neurons based on biophysical details. These models can reveal what happens if a particular ionic current is active or inactive. One can then ask what advantages are given on the visual system by having the particular class of ion channel present in the neuron.In this study, we analyzed the underlying mechanisms of a rod photoreceptor that behaves as a bandpass filter. The simulated frequency response revealed that a single rod behaves as a bandpass filter whose characteristics are affected by the stimulus strength and frequency. We analyzed the contribution of individual ionic currents to bandpass filtering and found that the filtering of small signals is largely regulated by the calcium-dependent currents, whereas the filtering of large signals is regulated by the hyperpolarization-activated current. The major discovery was that the kinetics of the ionic currents, IK(Ca), ICl(Ca), and Ih characterize the bandpass filtering of rod signals. We also developed a stochastic model of spike generation in retinal ganglion cells. The stochastic model succeeded to reproduce precise and reliable spikes to flucutuating current injection. We found the spike timing variability was much influenced by the outward K currents, IKv and IA.

脊椎动物的视网膜被认为是大脑的一个窗口，因为它的可及性和适用性适合神经科学研究。它被认为是脊椎动物大脑中为数不多的我们可以合理解释其用途及其工作原理的部分之一。视网膜是信息处理神经网络的理想模型，描述神经元如何相互作用以编码和处理视觉信息。在过去的十年中，我们基于生物物理细节开发了视网膜神经元的数学模型。这些模型可以揭示特定离子电流活跃或不活跃时会发生什么。然后人们可以问，神经元中存在特定类别的离子通道会给视觉系统带来哪些优势。在这项研究中，我们分析了充当带通滤波器的杆状光感受器的基本机制。模拟频率响应表明，单杆充当带通滤波器，其特性受到刺激强度和频率的影响。我们分析了单个离子电流对带通滤波的贡献，发现小信号的滤波很大程度上受钙相关电流的调节，而大信号的滤波则受超极化激活电流的调节。主要发现是离子电流 IK(Ca)、ICl(Ca) 和 Ih 的动力学表征了棒信号的带通滤波。我们还开发了视网膜神经节细胞中尖峰生成的随机模型。随机模型成功地重现了精确可靠的波动电流注入尖峰。我们发现尖峰时间变异性很大程度上受外向 K 电流、IKv 和 IA 的影响。