“…Treatment with NMDAR antagonists, such as ketamine, phencyclidine and MK801, induces SWM deficits (Beraki et al, 2009; Castane et al, 2015; Enomoto and Floresco, 2009; Verma and Moghaddam, 1996) and tends to reduce hippocampal theta oscillations, while enhancing PFC and hippocampal delta-, gamma- and high-frequency oscillations (130–180 Hz; Hinman et al, 2013; Hunt and Kasicki, 2013; Kjaerby et al, 2017; Korotkova et al, 2010; Lazarewicz et al, 2010; Moran et al, 2015; Sapkota et al, 2016). Acute and chronic ketamine treatment in rodents also alters the coupling of hippocampal theta phase with gamma- and high-frequency oscillation power (Caixeta et al, 2013; Michaels et al, 2018), reminiscent of the global and fronto-temporal frequency coupling alterations reported in patients with schizophrenia (Allen et al, 2011; Sun et al, 2013; Won et al, 2017). While the effects of NMDAR antagonists on long-range hippocampal-PFC synchrony are less clear (Lee et al, 2017), reports have shown that sub-anaesthetic doses of ketamine increase hippocampal-PFC functional connectivity measured using functional magnetic resonance imaging (fMRI) in rats (Gass et al, 2014) and humans (Grimm et al, 2015).…”