System-level analysis of organizational design principles underlying brain networks

Abstract

The brain is a multilevel complex system that consists of several levels of elements, from a neuronal level to a regional level, and functions through complex interactions between the elements at each level. Although the recent era of Connectomics has allowed us to determine the complex interconnectivity of the elements at each level, our understanding of organizational design principles underlying the resultant neuronal and regional brain networks is still lacking. In this dissertation, I investigated the organizational design principles underlying the complex brain networks by using systems biological approach. This dissertation contains two studies, each of which is conducted with the brain networks in neuronal level and regional level, respectively. In the first study, I constructed the spiking neural network model based on the specific connectivity rules of the three largest interneuron classes in the brain and explored the functional role of the network. Through the mathematical simulation analysis, I identified that this network is the core structure responsible for generation and modulation of neuronal oscillation dynamics. In the second study, I constructed the inter-regional structural brain network from MRI data and explored its organizational design principle from the network control perspective. Especially, the comparison between the inter-regional brain network and other real-world complex networks has made to explore the unique characteristic of the inter-regional brain network. As a result, I revealed that the inter-regional brain network is designed to have the unique control architecture that provides superior control robustness and control efficiency against other real-world complex networks. The analysis performed in this dissertation suggests the importance of the 'network neuroscience' approach in studying the brain and is expected to provide a fundamental basis for the development of specific therapeutic interventions and the development of brain-like artificial intelligence.