Center for Memory and Brain, Department of Psychology, Boston University, Boston, Massachusetts 02215, USA.
J Neurosci. 2010 Oct 13;30(41):13850-60. doi: 10.1523/JNEUROSCI.0547-10.2010.
One of the two primary classes of models of grid cell spatial firing uses interference between oscillators at dynamically modulated frequencies. Generally, these models are presented in terms of idealized oscillators (modeled as sinusoids), which differ from biological oscillators in multiple important ways. Here we show that two more realistic, noisy neural models (Izhikevich's simple model and a biophysical model of an entorhinal cortex stellate cell) can be successfully used as oscillators in a model of this type. When additive noise is included in the models such that uncoupled or sparsely coupled cells show realistic interspike interval variance, both synaptic and gap-junction coupling can synchronize networks of cells to produce comparatively less variable network-level oscillations. We show that the frequency of these oscillatory networks can be controlled sufficiently well to produce stable grid cell spatial firing on the order of at least 2-5 min, despite the high noise level. Our results suggest that the basic principles of oscillatory interference models work with more realistic models of noisy neurons. Nevertheless, a number of simplifications were still made and future work should examine increasingly realistic models.
网格细胞空间放电的两种主要模型之一使用动态调制频率的振荡器之间的干扰。一般来说,这些模型是根据理想化的振荡器(建模为正弦波)来表示的,这些振荡器在多个重要方面与生物振荡器不同。在这里,我们表明,两种更现实的、有噪声的神经模型(Izhikevich 的简单模型和一个内嗅皮层星状细胞的生物物理模型)可以成功地用作这种类型模型中的振荡器。当在模型中加入加性噪声,使得未耦合或稀疏耦合的细胞表现出现实的尖峰间隔方差时,突触和缝隙连接耦合都可以使细胞网络同步,产生相对变化较小的网络级振荡。我们表明,尽管噪声水平很高,但这些振荡网络的频率可以被很好地控制,以产生稳定的网格细胞空间放电,至少在 2-5 分钟的量级上。我们的结果表明,振荡干扰模型的基本原理适用于更现实的噪声神经元模型。然而,仍然进行了一些简化,未来的工作应该检查越来越现实的模型。