The quest for the most accurate estimation of the surface Laplacian has invigorated the prevalent understanding that a high spatial sampling of the EEG signal is necessary to avoid spatial aliasing and other topographic misrepresentations (e.g., Junghöfer et al., 1997; Nunez et al., 1994; Srinivasan et al., 1996, 1998b). However, this premise either dismisses the usefulness of low density EEG (i.e., less than 64 and more channels) outright, or it ignores the evidence that the surface Laplacian transform still renders more useful EEG measures than those derived from surface potentials. Undoubtedly, the usefulness needs to be determined with regards to the research objective for each application, which will likely be different for clinical or basic research questions and when focusing on individual or group data.
