Table 2 Graph theoretical features of functional connectivity networks

ldg

Link density of the graph

(2 × ne)/(nn × (nn - 1))

acc

Average of closeness centrality

(1/nn) ∑ _nn (sum of reciprocal distances from a node to all other nodes)

gcc

Graph clustering coefficient

(3 × number of triangles)/(number of connected triples of nodes)

rcc

Rich club coefficient

(ne_k)/(nn_k × (nn _k - 1))

smg

S-metric of graph

Sum of the nodal degree products for every edge.

acg

Algebraic connectivity of graph

Second smallest eigenvalue of the Laplacian of adjacency matrix.

eng

Energy of network graph

Sum of absolute values of the real components of eigenvalues of adjacency matrix.