Following early recommendations (Evans et al., 1993), most OERP studies have relied on peak and latency measures of “prominent” deflections in selected OERP waveforms, mostly at vertex (Cz) or neighboring midline (Fz, Pz) or lateral sites (C3/4) and usually referenced to linked ear lobes or linked mastoids (e.g., Krüger, Frasnelli, Bräunig, & Hummel, 2006; Lundström, Seven, Olsson, Schaal, & Hummel, 2006; Murphy et al., 2000; Pause et al., 2003). The use of multichannel EEG montages has largely been limited to mapping ERP or CSD1 topographies (Laudien et al., 2006, 2008) or showing LORETA source localizations (Lorig,Rigdon,& Poor, 2006).However, whereas inverse source localization algorithms, such as LORETA or BESA, have the potential for data simplification and clarification, these approaches provide genuinely model-dependent solutions that need to be cautiously considered, pending independent validation.
