Here we focus specifically on theta’s role in episodic memory. We restrict our focus to studies that employ some kind of episodic memory task (i.e. free recall, cued recall and recognition) and report effects on low frequency (~ 1–10 Hz) power or the prevalence of low frequency oscillations. To maintain a focus on theta effects in episodic memory, we exclude studies of working memory and those that only report measures of high-frequency activity. We treat studies of power and phase separately (see “What about theta phase?”), organizing our review according to recording method (invasive vs. noninvasive) and analytic approach (memory success contrast vs. associative memory contrast; see Figure 2).
