Departamento de Física, Universidade Federal de Santa Catarina, 88040-900, Florianópolis, Santa Catarina, Brazil.
Departamento de Engenharia Química e Engenharia de Alimentos, Universidade Federal de Santa Catarina, 88040-900, Florianópolis, Santa Catarina, Brazil.
Sci Rep. 2016 Jul 20;6:29561. doi: 10.1038/srep29561.
Activity in the brain propagates as waves of firing neurons, namely avalanches. These waves' size and duration distributions have been experimentally shown to display a stable power-law profile, long-range correlations and 1/f (b) power spectrum in vivo and in vitro. We study an avalanching biologically motivated model of mammals visual cortex and find an extended critical-like region - a Griffiths phase - characterized by divergent susceptibility and zero order parameter. This phase lies close to the expected experimental value of the excitatory postsynaptic potential in the cortex suggesting that critical be-havior may be found in the visual system. Avalanches are not perfectly power-law distributed, but it is possible to collapse the distributions and define a cutoff avalanche size that diverges as the network size is increased inside the critical region. The avalanches present long-range correlations and 1/f (b) power spectrum, matching experiments. The phase transition is analytically determined by a mean-field approximation.
大脑中的活动以神经元放电波的形式传播，即雪崩。这些波的大小和持续时间分布已经在体内和体外的实验中被证明具有稳定的幂律分布、长程相关性和 1/f(b)功率谱。我们研究了一种基于哺乳动物视觉皮层的雪崩生物激发模型，发现了一个扩展的类似临界区域——一个格里菲斯相——其特征是发散的敏感性和零阶参数。这个相位接近皮质中兴奋性突触后电位的预期实验值，表明临界行为可能存在于视觉系统中。雪崩并不是完全的幂律分布，但可以将分布折叠起来，定义一个截断的雪崩大小，在临界区域内，随着网络大小的增加，该大小会发散。雪崩具有长程相关性和 1/f(b)功率谱，与实验相符。相变可以通过平均场近似进行分析确定。
