Development of brain function theory and the frontier brain projects

Abstract

The governments of several countries have funded frontier brain projects in recent years, which thus raises important questions about the brain and brain research. What have we known about brain function and the recent development of brain function theory? How are the frontier brain projects developing? This article reviews the development of brain function theories from an interdisciplinary perspective and introduces three frontier brain projects. The functions of the prefrontal cortex, especially, the medial prefrontal cortex, and the mirror neuron system as well as default-mode network (DMN) have been extensively investigated since the beginning of the 21th century. The findings have expanded brain functional systems from the specific nervous system and nonspecific reticular system to four major brain function systems including specific, nonspecific, socio-cognitive, and DMN systems. The specific nervous system coordinates and cooperates with the nonspecific reticular system; the former represent an efficiently reflective action to stimulation only when the later provides an adaptive arousal. A time sharing operating system consists of the DMN and socio-cognitive system with a 180-degree phase difference between the two systems. The former performs any socio-cognitive task whereas the later only prepares for a new task. There is a common principle between localization theory of brain function and equipotentiality theory of brain function which applies to the four brain function systems. There are four principles for neural information processing: the principle of simultaneous existence of digital encoding and analog encoding, the principle of the simultaneous existence of multi-processing processes and multi-information streams, the principle of circular permutation and coupling between electrical transmit and biochemical transmit in processing of neural information, and the principle of relevance between neural and genetic information. The principles of brain functions based on protein are different from those of artificial machines based on electricity. Artificial intelligent machines do not work as well as biological system in complicated ecological environments, because due to the lack of the last two information processing principles. The unique features of the human brain are manifested in the integration of biological and social attributes, and its hierarchical modules as well as the containment among the modules. The uniqueness of human brain is not only represented in the big prefrontal cortex but also the hierarchical modules that have been precipitated in different time axes from 3.5 billion years of biological evolution to near 100 years of a person’s life span. The highest level is individual’s social conscious module including the mirror neural system and the theory of mind module (ToMM). The unique modules are developed starting from the 4th year. The functional principle of the matured health human brain is shaped by individuals’ socio-cultural experiences. Either artificial intelligent machines or animal intelligence lacks human socio-cultural environments, and thus the animal brain comprised of 3 hierarchical modules. The three frontier brain projects that are respectively characterized by marcroscopic, microscopic, and mesoscopic mapping include the brain connectome, brain activity map(BMP), and China Brain Project. Connectome project studies both brain structural and functional networks based on brain imaging data. BMP explores molecular or neuronal mechanisms of behavior based on new techniques in molecular biology and cell biology. China Brain Project aims to fill out the gaps between macro- and microscopic investigating project, based on new technique, to display a whole neuron connectome.