Figure 3: Depicts novel object recognition performance of mice (n = 12 / group) receiving intracerebroventricular (i.c.v.) infusions of saline or the opioid receptor antagonist, naloxone methiodide (NXM; 30 nmol), followed by intraperitoneal (i.p.) saline or the kappa opioid receptor agonist, U50,488 (0.3 mg / kg). * indicates significant interaction wherein mice in all groups spent a greater percentage of time with the novel object in Phase III except for saline-infused mice receiving U50,488 (0.3 mg / kg).