L: +/-1.5, D/V: -2.0; and 3) ventral to the original target site: A/P: -3.3, L: +/-1.5, D/V: -4.0 (Paxinos and Watson 2007). Subjects were given a two week recovery period after cannulae implantation before commencing the experiments. Each intracerebral infusion was administered in a volume of 0.5 μl over a 1 min period and the injector needle was left in each respective cannula for an additional 1 min. At the conclusion of each experiment, all rats were euthanized with pentobarbital overdose. The brains were removed from the skull, postfixed in -30°C isopentane (2-methylbutane), and frozen at -80°C. Coronal sections (40-μm) were then cut using a freezing microtome and Nissl stained with thionin. A dissecting microscope (Swift Instruments International, Tokyo, Japan) was used to visualize the location of the intracerebral injection sites, which were then verified according to a rat brain atlas (Paxinos and Watson 2007).
