Structural foundations of resting-state and task-based functional connectivity in the human brain

Abstract

Magnetic resonance imaging enables the noninvasive mapping of both anatomical white matter connectivity and dynamic patterns of neural activity in the human brain. We examine the relationship between the structural properties of white matter streamlines (structural connectivity) and the functional properties of correlations in neural activity (functional connectivity) within 84 healthy human subjects both at rest and during the performance of attention-and memory-demanding tasks. We show that structural properties, including the length, number, and spatial location of white matter streamlines, are indicative of and can be inferred from the strength of resting-state and task-based functional correlations between brain regions. These results, which are both representative of the entire set of subjects and consistently observed within individual subjects, uncover robust links between structural and functional connectivity in the human brain.uman cognitive function is supported by large-scale interactions between different regions of the brain. The anatomical scaffolding that mediates these interactions can be described by a structural connectome that maps the spatial layout of white matter (1). Structural connectivity (SC), defined by the physical properties of these direct anatomical connections, supports the relay of electrical signals between brain regions. Neurophysiological events can similarly be described by a functional connectome that maps coordinated changes in neuronal activity, field potentials, blood flow, or energy consumption (2). Functional connectivity (FC), defined by temporal correlations in such neurophysiological events, reflects the resting-state and task-dependent strengths of correlated activity in different brain regions (3-5). The estimation of structural and functional connectivity from different experimental techniques raises two complementary questions about the quantitative relationships between structural and functional connectomes: (i) to what extent can the resting-state and task-dependent strengths of functional correlations between brain regions be inferred from structural connectomes, and (ii) to what extent can the physical properties of anatomical connections be inferred from functional connectomes?Connectomes, whether examined at the neural or systems level, are networks whose structural properties, such as the length and number of connections, can differentially impact functional properties, such as local or global correlations in temporal dynamics. Whereas the length and density of anatomical connections are thought to impact functional processes such as information segregation and integration (6, 7), the extent to which such relationships are robustly observed in the human brain is not well understood. Previous studies have been limited in scope to specific anatomical connections and brain regions, small sample sizes, and resting-state neural activity (8-13) and have consequently left several fundamental questions unanswered. How do variations in structural features, such a...

Structurally-informed Bayesian functional connectivity analysis

“…This is confirmed by highly significant positive correlations between streamline count and absolute partial correlation values (ρ > 0.40, p < 10 −31 in all subjects). This relationship has been observed before (Hermundstad et al, 2013). This indicates that there is a clear correspondence between the information conveyed by the structural connectivity as estimated using DWI and the Bayesian functional connectivity analysis applied to resting-state fMRI data.…”

An Integrated Assessment of Changes in Brain Structure and Function of the Insula Resulting from an Intensive Mindfulness-Based Intervention

“…We first examined the effect of the intervention on cortical thickness across the entire cortical surface and then examined two specific regions of interest-the somatomotor and insular cortices-which have shown consistent structural changes as a function of mindfulness training as well as altered functional connectivity patterns following an intervention highly similar to the one reported here (Fox et al 2014;Mrazek et al 2016). Since structural changes likely underlie changes in function (Hermundstad et al 2013), we next examined whether brain regions exhibiting changes in cortical thickness also exhibited changes in their resting-state functional connectivity (rs-FC) with the rest of the brain. Patterns of rs-FC predict individual differences in cognitive abilities and are thought to reflect the repeated history of co-activation of brain regions (GuerraCarrillo, Mackey, & Bunge 2014).…”

Breakdown of the brain’s functional network modularity with awareness

“…When examining a large set of ROIs that encompass the different networks of the human cerebral cortex (21, 22), we can apply graph theory analyses to estimate the extent to which key measures of global information processing are altered by the state of awareness. This approach has been previously applied to study differences in cognitive states (23)(24)(25)(26)(27)(28)(29)(30)(31). Although recent studies have taken advantage of graph theory analysis to examine the connectivity patterns that precede a conscious event (32) or following pharmacologically induced loss of consciousness (33), this approach had yet to be used for characterizing the topology associated with conscious target perception per se, a necessary test for global theories of awareness.…”