CSD (Pizzagalli, 2007), although helpful CSD topography has been obtained from 19 scalp electrodes (Harmony et al., 1993; Fernandez-Bouzas et al., 1995, 1997; Ponomarev et al., 2014) or even less (Turetsky et al., 1998a, 1998b, 2000); and 3) it is often assumed that CSD mainly represents the activation patterns of the cortical surface and is relatively insensitive to the deep brain sources (e.g., Duffy and Als 2012), although it is suggested that this concern could be methodologically addressed by using a low resolution CSD (Tenke and Kayser, 2012).
