In laboratory rodents, administration of Δ9-THC disrupts hippocampal-dependent learned behavior in operant and spatial maze models of memory (Brodkin and Moerschbaecher 1997; Ferrari, et al 1999; Heyser, et al 1993; Lichtman, et al 1995; Mallet and Beninger 1998; Nakamura, et al 1991; Varvel, et al 2001). Behavioral studies have provided compelling support for the involvement of the hippocampus in cannabinoid-induced memory impairment. Hampson et al. (2000) reported that systemic administration of Δ9-THC or the synthetic cannabinoid receptor agonist, WIN 55,212-2, elicited deficits in a delayed non-match-to-sample operant task that were related to depressed hippocampal cell firing (Hampson and Deadwyler 2000). Several other groups have demonstrated that intrahippocampal administration of Δ9-THC, WIN55,212-2, or CP-55,940, a potent, bicyclic cannabinoid analogue impaired spatial memory in rat radial arm maze, delayed alternation t-maze, or water maze tasks (Egashira, et al 2002; Lichtman, et al 1995; Suenaga, et al 2008; Yim, et al 2008).
