The P3 component is not a unitary phenomenon. This wave arises from activity in multiple sources that form a network within the brain. Important contributions from the frontal cortex (including anterior cingulate), parietal cortex, and hippocampus have been described (Ardekani et al. 2002; Kiehl and Liddle 2001; Menon et al. 1997). The energy in the P3 wave largely consists of contributions from θ and δ oscillations elicited during cognitive processing of stimuli. The energy of the δ oscillations is concentrated toward the posterior regions of the scalp, whereas the θ oscillations are more frontocentral or anterior (see figure 1) (Basar-Eroglu et al. 1992; Karakas et al. 2000a,b; Yordanova and Kolev 1996).
