Similarly, early studies combining TMS with EEG demonstrated that single-pulse TMS to the motor cortex produced a complex sequence of successive activations, with EEG activity changes under the TMS coil occurring immediately, then spreading over a few milliseconds to ipsilateral motor, premotor and parietal regions, and then spreading several milliseconds later to the contralateral motor cortex (Ilmoniemi et al., 1997; Komssi et al., 2002), (Figure 5b). Subsequent studies utilizing fcEEG measures, such as coherence, have provided quantitative evidence that rTMS can alter the strength of the connection between different cortical regions (Jing & Takigawa, 2000; Plewnia et al., 2008); the behavioral significance of these changes is as yet unknown.
