Figure 4. .
Functional hubs constrain topological response to stimulation. (A) Distribution of 248 stimulation locations sampled across 94 subjects. (B) To examine the effect of stimulation location on the reconfiguration of functional network topology, we measure the node strength of the stimulation region during the baseline epoch—before any stimulation is delivered—for each coherence frequency band. Intuitively, nodes with low strength (left) tend to be functionally isolated and exhibit weak coherence with the other nodes in the network, while nodes with high strength (right) tend to be functional hubs and exhibit strong coherence with the other nodes in the network. We expect that stimulation of strong functional hubs will lead to a homogenous change in network topology, and we conversely expect that stimulation of weak functional hubs will lead to a heterogenous change in network topology. (C) Correlation between the stimulation node strength and the change in mean of node strengths. We find no significant relationship between the stimulation node strength and the change in mean of node strengths in any frequency band. (D) Correlation between the stimulation node strength and the change in variance of node strengths. We find no significant relationship between the stimulation node strength and the change in variance of node strengths. (E) Correlation between the stimulation node strength and the configuration similarity. Correlations are significantly positive in the low gamma band (p < 0.05, corrected) and in the high gamma band (p < 0.001, corrected). Greater stimulation node strength leads to greater configuration similarity (lower edge reconfiguration) in high-frequency networks. Correlations are computed over stimulation sessions across subjects. *p < 0.05, **p < 0.01, ***p < 0.001.