the average reference. It is also not a coincidence that low or zero spectral amplitudes (dark blue regions in Fig. 10B, C) can be seen over anterior regions (Nose, Nz) for the nose-referenced data but over lateral inferior temporal-parietal sites (TP9/10, P9/10) for the linked-mastoids reference, and zero amplitudes are suspiciously absent for the average reference. These spurious effects, which can be attributed to volume conduction, reference location and arithmetic (i.e., computation of an average reference), are considerably diminished by the surface Laplacian.
