Blair Hugh T, Wu Allan, Cong Jason
Psychology Department, UCLA, , Los Angeles, CA 90095, USA.
Philos Trans R Soc Lond B Biol Sci. 2013 Dec 23;369(1635):20120526. doi: 10.1098/rstb.2012.0526. Print 2014 Feb 5.
Theories of neural coding seek to explain how states of the world are mapped onto states of the brain. Here, we compare how an animal's location in space can be encoded by two different kinds of brain states: population vectors stored by patterns of neural firing rates, versus synchronization vectors stored by patterns of synchrony among neural oscillators. It has previously been shown that a population code stored by spatially tuned 'grid cells' can exhibit desirable properties such as high storage capacity and strong fault tolerance; here it is shown that similar properties are attainable with a synchronization code stored by rhythmically bursting 'theta cells' that lack spatial tuning. Simulations of a ring attractor network composed from theta cells suggest how a synchronization code might be implemented using fewer neurons and synapses than a population code with similar storage capacity. It is conjectured that reciprocal connections between grid and theta cells might control phase noise to correct two kinds of errors that can arise in the code: path integration and teleportation errors. Based upon these analyses, it is proposed that a primary function of spatially tuned neurons might be to couple the phases of neural oscillators in a manner that allows them to encode spatial locations as patterns of neural synchrony.
神经编码理论试图解释世界的状态是如何映射到大脑的状态上的。在此，我们比较动物在空间中的位置是如何由两种不同类型的脑状态进行编码的：由神经放电率模式存储的群体向量，与由神经振荡器之间的同步模式存储的同步向量。此前已经表明，由空间调谐的“网格细胞”存储的群体编码可以展现出诸如高存储容量和强容错能力等理想特性；在此表明，缺乏空间调谐的有节奏爆发的“θ细胞”所存储的同步编码也能实现类似特性。由θ细胞组成的环形吸引子网络的模拟表明，与具有相似存储容量的群体编码相比，同步编码如何能用更少的神经元和突触来实现。据推测，网格细胞和θ细胞之间的相互连接可能控制相位噪声，以纠正编码中可能出现的两种错误：路径积分和瞬移错误。基于这些分析，有人提出，空间调谐神经元的主要功能可能是以一种允许它们将空间位置编码为神经同步模式的方式来耦合神经振荡器的相位。
