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Fig. 9.3. Relationship of structural connectivity and functional connectivity in the human brain
(data replotted from Hagmann et al ., 2008). Scatter plots show strengths of structural connections
versus strengths of functional connections within a lower-resolution network of 66 anatomical
subregions. Structural connections were obtained from diffusion imaging, while functional
connections were obtained from functional MRI during the resting state. For specific regions
(precuneus and posterior cingulated, left panel) as well as across the entire brain (right panel)
structural connections are highly predictive of functional connections. For details, please see
Hagmann et al ., 2008.
Computational models can provide some insights into how structural
connections may shape statistical dependencies between parts of the brain at
multiple time scales. Because computational models allow the introduction of
systematic variations in connectivity, these approaches allow the systematic
study of how neural dynamics is shaped by the structure of connection patterns
linking individual elements,. Detailed computer simulations of cortical networks
have been carried out with heterogeneous (Jirsa and Kelso, 2000; Jirsa 2004;
Assisi et al ., 2005) and spatially patterned (Sporns, 2004) connection topologies.
These studies demonstrated that different connection topologies can generate
different modes of neuronal dynamics. For example, as discussed above,
connectivity patterns containing locally clustered connections with a small
admixture of long-range connections were shown to exhibit robust small-world
attributes (Sporns and Zwi, 2004; Sporns, 2004; Kaiser and Hilgetag, 2006),
while conserving wiring length. These connectivity patterns also gave rise to
functional connectivity of high complexity (Tononi et al ., 1994; Sporns et al .,
2000) characterized by the coexistence of spatially segregation (regional
specialization) and global integration (system-wide interactions that unify
processing across segregated clusters). These computational studies suggest the
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