The location of the tip of the injection cannula in rats treated with sense or antisense oligonucleotides in the prelimbic/infralimbic subregion of the medial prefrontal cortex. Three groups of animals are represented here. A, Rats treated 12 hr before the acquisition session and killed for immunocytochemistry. B, Rats treated 72 hr before the acquisition session and killed for immunocytochemistry.C, Rats treated 12 hr before acquisition and tested for expression 72 hr later. The brain drawings are from Paxinos and Watson (1997), and the numbers represent the location of the section in millimeters anterior to bregma.