Stroke, once the prime example of how a focal brain lesion can lead to a neurological deficit, is being increasingly recognized as a disorder of interacting brain networks (Grefkes et al., 2008; Carter et al., 2010; van Meer et al., 2010). Hemiparesis has been related to reduced interhemispheric connectivity during rest (Carter et al., 2010), as well as reduced effective connectivity between the supplementary motor area and primary motor area (M1) during hand movements, both of which are correlated with the severity of the movement deficit (Grefkes et al., 2008). Neglect has been related to decreased connectivity within the dorsal and ventral attention networks (He et al., 2007b; Carter et al., 2010). Not only does the severity of neglect correlate with these connectivity abnormalities, but recovery of neglect over time is associated with restoration of normal connectivity patterns (He et al., 2007b). Similarly, EEG studies have demonstrated changes in functional connectivity within both the ipsilesional hemisphere and the contralesional hemisphere (as well as the connections between them) after ischemic stroke (Gerloff et al., 2006; Zhu et al., 2009).
