The most commonly studied coupling is between the amplitude in the gamma band and the phase in the theta range (gamma/theta). This has been associated with activity in the hippocampus and performance in memory tasks in rodents (Tort et al., 2009; Canolty and Knight, 2010; Lisman and Jensen, 2013) and has been shown to be vital for working memory in humans (Axmacher et al., 2010). In rodent models of AD, studies have found that impaired gamma/theta coupling arises before amyloid beta accumulation (Goutagny et al., 2013) and attenuated gamma/theta coupling in knock-out mice (Zhang et al., 2016; Bazzigaluppi et al., 2018). Studies investigating patients with AD have found diverging results (Poza et al., 2017; Wang et al., 2017). One study found a decrease in CFC (Poza et al., 2017), while another found an increased CFC (Wang et al., 2017) in AD compared to healthy controls (HC). Furthermore, one study found that CFC was decreased in both AD and MCI compared with HC and associated with working memory deficits (Goodman et al., 2018). The underlying reason for the diverging results may
