As summarized above (see section, “Studying Brain Networks in Humans”), much recent work has suggested that cognitive functions are carried out by a dynamic network of interacting brain regions. The integration of brain stimulation techniques and neuroimaging enables further identification and evaluation of these dynamic network interactions. TMS changes neural activity directly in a spatially and temporally focused manner. By studying how the changes induced by TMS are then propagated throughout the rest of the brain, the connectivity of the stimulated brain region can be causally assessed, and the results compared with the findings of traditional functional connectivity analysis (Pascual-Leone et al., 2000; Paus, 2005; Lee et al., 2006; O’Shea et al., 2008; Bestmann et al., 2008; Miniussi & Thut, 2010). Furthermore, since different rTMS and tDCS protocols produce somewhat long-lasting changes in neural activity in a relatively predictable manner, noninvasive brain stimulation techniques permit the directed manipulation of neural activity. The potential implications for our understanding and treatment of network dysfunction in neuropsychiatric diseases are significant.
