Relative power time courses and topographical map series in the θ band were obtained by computing the average absolute θ power at each time point in the ERONPL TFRs, and normalizing this by the relative θ power using either Equation 1 or 2. Relative percentage power time courses (Equation 1) are a typical way of displaying ERO dynamics in the literature and are referred to as ERD / ERS time courses (Pfurtscheller and Lopes da Silva, 1999). Time courses displayed as log ratios of the absolute power at a particular time point relative to the reference power (Equation 2) have also been utilized in the literature. Makeig (1993) refers to these as the event-related spectral perturbation (ERSP).
