Despite these reported and often unsupported limitations, the proven and potential utilities of CSD are well-recognized for several key reasons. The fact that the surface Laplacian mapping approach does not require knowledge of conductivity distribution inside the subject's head provides an easy-to-use methodology by improving the spatial resolution of the conventional EEG (He et al., 2001). CSD, as a conservative description of neural current generators (Tenke and Kayser, 2012), has been implemented for all electrophysiological methods (EEG, ERPs, and EROs) and measures (amplitude, phase, power, and coherence), and provides a unique and important tool for understanding brain sources in a variety of contexts, ranging from basic research to clinical applications. For example, Srinvasan et al. (2007) suggest that moderate to large EEG coherence can also arise simply by the volume conduction of current through the tissues of the head, and therefore the coherence measure appears to result from a mixture of volume conduction effects and genuine source coherence. Therefore, surface Laplacian methods are the available best options to minimize the effect of volume conduction on coherence estimates. Further, according to
