surface potentials, resulting in a diffuse midline maximum. Furthermore, despite preserving the relative topographic distribution of ERP values when using different reference schemes, in case of the auditory N1, a linked-mastoids reference will largely eliminate positive values across the recording montage, which may further mask the underlying bihemispheric activation pattern. Another important observation is that the CSD topographies clearly reflect the well-known anatomical differences between the two hemispheres, involving asymmetries of the planum temporale posterior to Heschl’s gyrus (primary auditory cortex) within the Sylvian fissure (e.g., Galaburda, 1995; Geschwind and Levitsky, 1968; Witelson and Kigar, 1988), which affect both location and orientation of the neuronal generators underlying auditory N1.
