Thus, both neurophysiological techniques, such as EEG, and neuroimaging techniques, such as fMRI, have been used to assess the functional connectivity of the human brain during both the resting state and during task activity, and to explore the structure of brain activity. Furthermore, alterations in functional connectivity have been associated with several neuropsychiatric diseases. Consequently, there is a pressing need for tools that enable more precise study and manipulation of human cortical networks in vivo. Noninvasive brain stimulation techniques hold significant promise in this regard. Manipulation of diffuse neurotransmitter systems through pharmacological therapy may prove useful in normalizing altered network dynamics (Anand et al., 2005a). However, brain network dynamics in health and disease may be more directly addressed through spatially and temporally more specific and more precisely quantifiable interventions such as TMS or tDCS.
