Brain networking analysis In MA patients, the networking model seemed to be more concentrated within the parietal-occipital cluster of connections, especially under high spatial frequency stimulation, with a more evident segregation of information into the posterior areas.
During visual stimulation, both MA and MO showed increased information transfer toward the fronto-central regions, while MA patients showed a segregated cluster of connections in the posterior regions, and an increased bold signal in the visual cortex, more evident at 2 cpd spatial frequency.
They are both highly non-random networks with a "small world" architecture, meaning that there is both dense clustering of connections between neighbouring nodes and enough long-range short cuts to facilitate communication between distant nodes.
It is apparent that such constraints on the geographical distance spanned by links between nodes (viz., cost of wiring length) can give rise to clustering of connections among physically adjacent elements.
This could lead to the increased clustering of connections seen in groups of 3 6 neurons (see also Yassin et al. 2010).
Since the high clustering of connections between nodes in the same module will favor low wiring cost, modular networks may be of the property of small-worldness which is advantageous for nervous system design [ 32].
This seems to be especially the case when networks display a 'small-world topology', which is characterized by a local clustering of connections and a short path length between any pair of nodes (Sporns et al., 2005; Achard and Bullmore, 2007; Fornito et al., 2010).
To relate a gene cluster to its corresponding endophenotype, we first computed the weighted sum of genes in a cluster for connection weights, and then correlated it with the endophenotype output.
Although the co-expression network separates different super-clusters, interpretation of connections among the nodes remained intractable due to the large size of this network.
Different types of cluster connection are described and several examples of final fractal structures are given.
