Fos counts normalised across both brain hemispheres for each brain region are shown for the novel and the familiar hemispheres for sense or antisense ODN-treated rats for the following regions: perirhinal cortex (PRH), temporal association cortex (Te2), auditory cortex (AU) and entorhinal cortex (ENT). Following infusions of sense Fos ODN (control) into the perirhinal cortex there is a differential expression of Fos in response to viewing novel or familiar images in the perirhinal cortex (in agreement with previous studies): repeated measures ANOVA effect of novelty/familiarity: * p < 0.05, ** p < 0.01. After infusion of antisense Fos ODN the differential expression of Fos within the perirhinal cortex is disrupted: repeated measures ANOVA interaction of treatment and novelty/familiarity: †† p < 0.01. In PRH, a significant interaction between novelty/familiarity and ODN treatment was found. In both sense and antisense groups, Fos counts in Te2 were higher in the novel than the familiar hemisphere.