Functional connectivity is just temporally correlated neural activation (technically for fmri we are measuring blood oxygenation, but whatever). So we might hav

Functional connectivity is just temporally correlated neural activation (technically for fmri we are measuring blood oxygenation, but whatever). So we might have regions a, b, c and d, and find that a and b tend to be co-activated, but that c tends to de-activate when a or b are activated, while d's activity is uncorrelated with any of the others. For example, insula and dorsal anterior cingulate cortex are usually positively corellated with each other, but negatively correlated with regions of the default mode network. Modulation just means that the manipulation, in this case modafinil, changed the correlation between neural activation in different brain regions, in this case between cortical regions and the cerebellum.