Roy Sisir, Llinás Rodolfo
Physics and Applied Mathematics Unit, Indian Statistical Institute, Calcutta, India.
Prog Brain Res. 2008;168:133-44. doi: 10.1016/S0079-6123(07)68011-X.
Pellionisz and Llinás proposed, years ago, a geometric interpretation towards understanding brain function. This interpretation assumes that the relation between the brain and the external world is determined by the ability of the central nervous system (CNS) to construct an internal model of the external world using an interactive geometrical relationship between sensory and motor expression. This approach opened new vistas not only in brain research but also in understanding the foundations of geometry itself. The approach named tensor network theory is sufficiently rich to allow specific computational modeling and addressed the issue of prediction, based on Taylor series expansion properties of the system, at the neuronal level, as a basic property of brain function. It was actually proposed that the evolutionary realm is the backbone for the development of an internal functional space that, while being purely representational, can interact successfully with the totally different world of the so-called "external reality". Now if the internal space or functional space is endowed with stochastic metric tensor properties, then there will be a dynamic correspondence between events in the external world and their specification in the internal space. We shall call this dynamic geometry since the minimal time resolution of the brain (10-15 ms), associated with 40 Hz oscillations of neurons and their network dynamics, is considered to be responsible for recognizing external events and generating the concept of simultaneity. The stochastic metric tensor in dynamic geometry can be written as five-dimensional space-time where the fifth dimension is a probability space as well as a metric space. This extra dimension is considered an imbedded degree of freedom. It is worth noticing that the above-mentioned 40 Hz oscillation is present both in awake and dream states where the central difference is the inability of phase resetting in the latter. This framework of dynamic geometry makes it possible to distinguish one individual from another. In this paper we shall investigate the role of dynamic geometry in brain function modeling and the neuronal basis of consciousness.
佩利奥尼斯和利纳斯多年前提出了一种用于理解大脑功能的几何解释。这种解释假定大脑与外部世界之间的关系是由中枢神经系统(CNS)利用感觉和运动表达之间的交互几何关系构建外部世界内部模型的能力所决定的。这种方法不仅在大脑研究中开辟了新视野,也为理解几何本身的基础带来了新契机。名为张量网络理论的这种方法足够丰富,能够进行特定的计算建模,并基于系统的泰勒级数展开特性,在神经元层面解决预测问题,将其作为大脑功能的一个基本属性。实际上有人提出,进化领域是内部功能空间发展的支柱,这个内部功能空间虽然纯粹是表征性的,但能与所谓“外部现实”这个截然不同的世界成功互动。现在,如果内部空间或功能空间具有随机度量张量属性,那么外部世界中的事件与其在内部空间中的表征之间就会存在动态对应关系。我们将这种动态几何称为动态几何,因为大脑的最小时间分辨率(10 - 15毫秒)与神经元及其网络动态的40赫兹振荡相关,被认为负责识别外部事件并产生同时性的概念。动态几何中的随机度量张量可以写成五维时空,其中第五维既是概率空间也是度量空间。这个额外维度被视为一种嵌入的自由度。值得注意的是,上述40赫兹振荡在清醒和梦境状态中都存在,两者的主要区别在于后者无法进行相位重置。这种动态几何框架使得区分个体成为可能。在本文中,我们将研究动态几何在大脑功能建模中的作用以及意识的神经元基础。