Fig. 9.

Arc expression is depressed in the hippocampus after unilateral lesions of the fimbria–fornix. A, Pattern of Arc expression as revealed by nonisotopic in situ hybridization in the posterior hippocampus contralateral to the fimbria–fornix lesion (FFX Contra).B, Pattern of expression ipsilateral to the lesion (FFX Ipsi). Brains were sectioned in the horizontal plane so as to confirm the completeness of the lesion. Note low levels of Arc expression in the hippocampus and dentate gyrus (DG) and the high levels of expression in the adjacent cerebral cortex (Cortex) and the posterior subiculum (Sub).