Contribution of Exploratory Methods to the Investigation of Extended Large-Scale Brain Networks in Functional MRI: Methodologies, Results, and Challenges

Figure 1

Example of extended large-scale networks extracted in fMRI at rest. The six networks were identified using spatial ICA and a hierarchical clustering approach similar to that of [79] on a group of 20 healthy subjects acquired at rest. Networks—M/SM: motor/sensorimotor, V: visual, DM: default mode, dAtt: dorsal attentional, vAtt: ventral attentional, EC: executive control. The auditory network was not found as a separate network but some temporal regions of the primary auditory cortex are overlapped by other networks (in particular the M/SM network and the two attentional networks). The union of all networks does not add up to comprise the entire brain; for instance, some parts of the frontal cortex do not belong to any reported networks. By contrast, some brain regions simultaneously belong to several networks (in black).