Theta-band activity dominates the EEG signal recorded from the hippocampus of most non-human mammals during wakefulness, and intracranial recordings suggest that theta activity in humans is modulated by behavior in similar ways (Steriade et al., 1990). Hippocampal theta activity, which is thought to reflect an “on-line” state of the hippocampus (Buzsaki, 2002), appears to be related to long-term potentiation and thus to memory consolidation (Steriade et al., 1990). Theta oscillations have also been observed in prefrontal cortex (PFC) (Benchenane, Tiesinga, & Battaglia, 2011). In rodents, coherent theta oscillations between hippocampus and PFC are critical for spatial working memory and encoding relevant information for long-term storage (Benchenane et al., 2010). In humans, theta oscillations in the prefrontal cortex have been linked to working memory performance (Tesche & Karhu, 2000), and theta activity in the resting EEG has been reported to be associated with reward sensitivity and decision-making that is compromised by preference for immediate reward (Massar, Kenemans, & Schutter, 2013; Schutter & Van Honk, 2005).
