The Human Brain Network

Abstract

This article summarizes recent empirical findings and modeling approaches aimed at unraveling the structure of the human brain network. The physical structure of the human brain is still only partially mapped and how structural brain connectivity gives rise to functional brain dynamics is only incompletely understood. Initial mapping studies indicate that the human brain forms a smallworld architecture that is structurally organized into modules interlinked by hub regions. This connectivity structure shapes endogenous dynamics as well as responses of the brain to external perturbations. Thus, the topology of the human brain network may be an important ingredient in brain function. We will briefly discuss how complex brain networks may shape human cognition in the healthy and the diseased brain. IntroductionModern neuroscience allows the simultaneous recording and analysis of large numbers of neurons, and even of neural activity across the entire human brainyet our understanding of how the brain functions as an integrated system organized into a complex biological network is still in its infancy. Nevertheless, the material presented in this chapter argues that complex network approaches (Strogatz, 2001;Amaral and Ottino, 2004;Boccaletti et al., 2006) may provide a fundamental basis for our understanding of brain function (see also Sporns and Tononi, 2007). In recent years network science approaches have offered significant new insights into how the structure of the brain shapes its dynamics and how the elements of a neural network can make different contributions to brain function on the basis of how they are interconnected. The dichotomy between brain structure and dynamics presents unique challenges to network approaches. A comprehensive analysis of brain networks needs to address the central issue of how functional brain networks (represented as dynamic linkages between parts of the brain that are transient in nature) can Handbook on Biological Networks Downloaded from www.worldscientific.com by NANYANG TECHNOLOGICAL UNIVERSITY on 08/28/15. For personal use only.

Abnormal structural connectivity in the brain networks of children with hydrocephalus

“…Human brain organization can be considered as a series of anatomically segregated regions, with all the regions connected by WM fibers that transfer information among them ( Sporn, 2009 ). As described by Guye et al (2010) , there are many different types of networks based on their distinct topological network features.…”

From static to temporal network theory: Applications to functional brain connectivity

“…In the case of A i , j = A j , i , for all i and j , the matrix is considered undirected ; when this is not the case, the matrix is directed . With static networks, many different properties regarding the patterns of connectivity between nodes can be quantified, for example through centrality measures, hub detection, small-world properties, clustering, and efficiency (see Newman, 2010 ; Sporns, 2009 ; Bullmore & Sporns, 2009 , for detailed discussion).…”

“…It is well known that the brain’s large-scale activity is organized into networks. The underlying organization of the brain’s infrastructure into networks, at different spatial levels, has been dubbed the brain’s functional and structural connectome ( Sporns, 2009 ; Sporns, Tononi, & Kotter, 2005 ). Functional connectivity, derived by correlating the brain’s activity over a period of time, has been successfully applied in both functional magnetic resonance imaging (fMRI; Greicius, Krasnow, Reiss, & Menon, 2003 ; Fransson, 2005 ; Fox et al, 2005 ; Smith et al, 2009 ) and magnetoencephalography (MEG; de Pasquale et al, 2010 ; Brookes et al, 2011 ; Hipp, Hawellek, Corbetta, Siegel, & Engel, 2012 ), yielding knowledge about functional network properties ( Buckner et al, 2009 ; Power et al, 2011 ; Power, Schlaggar, Lessov-Schlaggar, & Petersen, 2013 ; Nijhuis, van Cappellen van Walsum, & Norris, 2013 ) that has been applied to clinical populations ( Fox & Greicius, 2010 ; Zhang & Raichle, 2010 ).…”

Estimated EEG functional connectivity and aperiodic component induced by vagal nerve stimulation in patients with drug-resistant epilepsy

“…Although with limitations represented by volume conduction and the effects of field diffusion compared with source studies ( 10 ), surface neurophysiological techniques support the study of functional connectivity (Fc) between different neuronal groups underlying the electroencephalogram (EEG) electrodes placed on the scalp. Fc describes statistical dependency patterns of different electrodes in a selected time series ( 11 ) and is highly time-dependent because it is modulated by external stimuli ( 12 ).…”