Kozma Robert, Freeman Walter J
College of Information and Computer Sciences, University of MassachusettsAmherst, MA, USA; Department of Mathematical Sciences, University of MemphisMemphis, TN, USA.
Department of Molecular and Cell Biology, University of California at Berkeley Berkeley, CA, USA.
Front Syst Neurosci. 2017 Mar 14;11:10. doi: 10.3389/fnsys.2017.00010. eCollection 2017.
Measurements of local field potentials over the cortical surface and the scalp of animals and human subjects reveal intermittent bursts of beta and gamma oscillations. During the bursts, narrow-band metastable amplitude modulation (AM) patters emerge for a fraction of a second and ultimately dissolve to the broad-band random background activity. The burst process depends on previously learnt conditioned stimuli (CS), thus different AM patterns may emerge in response to different CS. This observation leads to our cinematic theory of cognition when perception happens in discrete steps manifested in the sequence of AM patterns. Our article summarizes findings in the past decades on experimental evidence of cinematic theory of cognition and relevant mathematical models. We treat cortices as dissipative systems that self-organize themselves near a critical level of activity that is a non-equilibrium metastable state. Criticality is arguably a key aspect of brains in their rapid adaptation, reconfiguration, high storage capacity, and sensitive response to external stimuli. Self-organized criticality (SOC) became an important concept to describe neural systems. We argue that transitions from one AM pattern to the other require the concept of phase transitions, extending beyond the dynamics described by SOC. We employ random graph theory (RGT) and percolation dynamics as fundamental mathematical approaches to model fluctuations in the cortical tissue. Our results indicate that perceptions are formed through a phase transition from a disorganized (high entropy) to a well-organized (low entropy) state, which explains the swiftness of the emergence of the perceptual experience in response to learned stimuli.
对动物和人类受试者的皮质表面及头皮上的局部场电位进行测量,结果显示存在间歇性的β和γ振荡爆发。在爆发期间,窄带亚稳态幅度调制(AM)模式会在几分之一秒内出现,并最终消散为宽带随机背景活动。爆发过程取决于先前学习到的条件刺激(CS),因此针对不同的CS可能会出现不同的AM模式。当感知以AM模式序列中体现的离散步骤发生时,这一观察结果引出了我们的认知电影理论。我们的文章总结了过去几十年中关于认知电影理论的实验证据及相关数学模型的研究发现。我们将皮质视为耗散系统,它们在接近临界活动水平(即非平衡亚稳态)时会进行自我组织。临界性可以说是大脑快速适应、重新配置、高存储容量以及对外部刺激敏感反应的一个关键方面。自组织临界性(SOC)已成为描述神经系统的一个重要概念。我们认为,从一种AM模式转变为另一种AM模式需要相变的概念,这超出了SOC所描述的动力学范畴。我们采用随机图论(RGT)和渗流动力学作为基本数学方法来模拟皮质组织中的波动。我们的结果表明,感知是通过从无序(高熵)到有序(低熵)状态的相变形成的,这解释了对学习到的刺激做出反应时感知体验迅速出现的原因。