This work was supported by selleck products a Grant-in-Aid for Scientific Research on Priority Areas from MEXT, Japan (K. Mori and M.Y.), and a Grant-in-Aid for Scientific Research from JSPS (K. Mori and M.Y.). “
“The medial prefrontal cortex (mPFC) has been implicated in the regulation and expression of defensive behaviors in rodents, including learned fear and its extinction (Burgos-Robles et al., 2007) as well as innate anxiety (Deacon et al., 2003, Lacroix et al., 2000, Shah et al., 2004, Shah and Treit, 2003 and Shah and Treit, 2004). Our prior work has suggested that during the expression of innate anxiety,

the mPFC works in concert with a major input source, the ventral hippocampus (vHPC) (Adhikari et al., 2010b). Whether and how neural activity in the mPFC

relates to anxiety-like behavior is unclear. During cognitive tasks, single-unit recordings in the mPFC have task-related firing patterns (Gemmell et al., 2002, Jones and Wilson, 2005, Jung et al., 1998, Pratt and Mizumori, 2001 and Sigurdsson et al., 2010) as well as functional interactions with the hippocampus (Jones and Wilson, 2005, Siapas et al., 2005, Sigurdsson et al., 2010 and Taxidis et al., 2010). However, it is unknown if mPFC activity is modulated by anxiety-related task features. Furthermore, the relationship between task-related firing patterns and functional coupling with the hippocampus is unclear. The elevated plus maze (EPM) is an extensively studied test of innate anxiety selleck chemical in rodents (Hogg, 1996). The EPM is conducted in a plus-shaped maze with four arms, two Dipeptidyl peptidase of which are enclosed by high walls and two of which are left open. Wild-type mice generally make fewer entries into and spend less time exploring the aversive open arms, compared to the relatively safe closed arms. Both the mPFC (Gonzalez et al., 2000 and Shah and Treit, 2004) and vHPC (Bannerman et al., 2002, Bannerman et al., 2004 and Kjelstrup et al., 2002) have been shown to be required for normal anxiety-related behaviors in the EPM. The monosynaptic unidirectional projection from the vHPC to the mPFC (Parent et al., 2010 and Verwer et al.,

1997) suggests the possibility that these two areas may be part of a functional circuit involved in anxiety-related behavior. Consisent with this notion, we recently found that theta-frequency (4–12 Hz) synchrony between the mPFC and the vHPC tracked and predicted anxiety-related behavior in the EPM (Adhikari et al., 2010b). These findings lead to following hypotheses: that mPFC neurons represent the anxiety-related features of the EPM; that this representation arises due to input from the vHPC; and that this representation is used by the animal to guide anxiety-related behavior in the maze. To test these hypotheses, we recorded mPFC single units and vHPC local field potentials from mice during exploration of standard and modified EPMs.