An additional theme is that developmental increases in functional connectivity tend to take place between portions of the brain that are functionally related in adults. This trend is most apparent in the network structures of task control and default networks in multiple studies by Fair et al. (Fair et al., 2008; Fair et al., 2009; Fair et al., 2007a), the seed maps of Kelly et al. (Kelly et al., 2009), and in the increasing partial correlations within the DMN noted by Supekar et al. (Supekar et al., 2010). Neuronal firing patterns are known to modify synaptic weighting (Miltner et al., 1999), and one possible explanation for the increases in coherent rs-fcMRI signal between functionally related brain regions is that the signal arises from shared histories of spontaneous or evoked activity. Recent studies have demonstrated that visual perceptual learning can influence rs-fcMRI signal in adults, lending credence to this hypothesis (Lewis et al., 2009). On the other hand, rs-fcMRI signal correlations may facilitate shared processing between brain regions, and may actually participate in the development of the functional capabilities of brain circuitry (Bi and Poo, 1999; Fiser et al., 2004; Varela et al., 2001).
