Liljenström Hans
Biometry and Systems Analysis, ET, SLU, Uppsala, Sweden and Agora for Biosystems, Sigtuna, Sweden.
Chaos. 2018 Oct;28(10):106319. doi: 10.1063/1.5044510.
One of the greatest challenges to science, in particular, to neuroscience, is to understand how processes at different levels of organization are related to each other. In connection with this problem is the question of the functional significance of fluctuations, noise, and chaos. This paper deals with three related issues: (1) how processes at different organizational levels of neural systems might be related, (2) the functional significance of non-linear neurodynamics, including oscillations, chaos, and noise, and (3) how computational models can serve as useful tools in elucidating these types of issues. In order to capture and describe phenomena at different micro (molecular), meso (cellular), and macro (network) scales, the computational models need to be of appropriate complexity making use of available experimental data. I exemplify by two major types of computational models, those of Hans Braun and colleagues and those of my own group, which both aim at bridging gaps between different levels of neural systems. In particular, the constructive role of noise and chaos in such systems is modelled and related to functions, such as sensation, perception, learning/memory, decision making, and transitions between different (un-)conscious states. While there is, in general, a focus on upward causation, I will also discuss downward causation, where higher level activity may affect the activity at lower levels, which should be a condition for any functional role of consciousness and free will, often considered to be problematic to science.
科学，尤其是神经科学面临的最大挑战之一，是理解不同组织层次的过程如何相互关联。与此问题相关的是波动、噪声和混沌的功能意义问题。本文探讨三个相关问题：（1）神经系统不同组织层次的过程可能如何关联；（2）非线性神经动力学的功能意义，包括振荡、混沌和噪声；（3）计算模型如何能成为阐明这类问题的有用工具。为了捕捉和描述不同微观（分子）、中观（细胞）和宏观（网络）尺度的现象，计算模型需要具有适当的复杂性，并利用现有的实验数据。我以两种主要类型的计算模型为例，即汉斯·布劳恩及其同事的模型和我自己团队的模型，这两种模型都旨在弥合神经系统不同层次之间的差距。特别是，对噪声和混沌在这类系统中的建设性作用进行了建模，并将其与感觉、感知、学习/记忆、决策以及不同（非）意识状态之间的转换等功能联系起来。虽然总体上关注向上因果关系，但我也将讨论向下因果关系，即较高层次的活动可能影响较低层次的活动，这应该是意识和自由意志的任何功能作用的一个条件，而意识和自由意志通常被认为对科学来说是有问题的。
