In the absence of an experimental task, these networks show a tight spatial correspondence with the neuronal circuits activated during cognitive, emotional, and sensorimotor tasks.30 Moreover, connectivity strength within these networks “at rest” has been related to cognitive and emotional state,28,31 further supporting resting-state fMRI as a tool to investigate symptoms and deficits in the context of disease. Functional networks can also be investigated within a graph theoretical framework (see section 2.4) by defining brain regions as the network nodes (e.g., through atlas-based or functional brain parcellation) and the temporal correlation strengths between node pairs as the weighted edges.
