While these studies have demonstrated P3-AR’s potential as an endophenotype for alcoholism, there has long been evidence that multiple processes compose the P3 (e.g. Dien, Spencer, & Donchin, 2003; Mantini, Corbetta, Perrucci, Romani, & Del Gratta, 2009), suggesting that conventional P3 measures (e.g. peak amplitude) may not be an optimal representation of the processes involved in P3-AR. An emerging approach to this problem is time-frequency (TF) decomposition, which has been used to show that ERP activity during the P3 can be characterized by two primary TF components: theta (3–7 Hz) and delta (0–3 Hz) (Basar-Eroglu, Basar, Demiralp, & Schurmann, 1992; E. M. Bernat, Malone, Williams, Patrick, & Iacono, 2007; Demiralp, Ademoglu, Istefanopulos, Basar-Eroglu, & Basar, 2001; Jones et al., 2006; Yordanova, Devrim, Kolev, Ademoglu, & Demiralp, 2000). Theta in the P3 window has been attributed to frontal neural generators, and has been considered to index focused attention and memory encoding processes (Basar-Eroglu et al., 1992; Klimesch, 1999; Yordanova et al., 2000). P3-related delta, which tends to be parietally maximal, has been considered to index signal matching, decision-making, and memory updating (Basar-Eroglu et al., 1992; Karakas, Erzengin, & Basar, 2000).
