Surgical and electrophysiological recording procedures performed in this study were previously described (Ehlers et al., 1999). In brief, P and NP rats were deeply anesthetized with Nembutal (50 mg/kg, intraperitoneally) and surgically prepared with recording electrodes at least two weeks prior to the experimental procedures. Stainless steel single-wire electrodes were implanted into the dorsal hippocampus (AP: −3.0 mm, ML: ±3.0 mm, DV: −3.0 mm) and amygdala (AP: 1.0 mm, ML: ±5.3 mm, DV: −8.5 mm) (Pellegrino et al., 1979). A 23-gauge stainless steel guide cannula was also aimed at the lateral ventricle (AP: −1.0 mm, ML: ±1.5 mm, DV: −4.6 mm). Screw electrodes were placed in the skull overlying the frontal (AP: 3.0 mm, ML: ±3.0 mm) and parietal (AP: −3.0 mm, ML: ±4.0 mm) cortices. A midline screw “reference” electrode was placed 3 mm posterior to lambda in the skull overlying the cerebellum. Electrode connections were made to a multipin Amphenol connector and the assembly was anchored to the skull with dental acrylic and anchor screws. EEG signals were recorded with a band pass of 0.5–70 Hz with a
