Induction of Arc expression in different subdivisions of the hippocampus after a 1-hr-long period of exploration of a novel complex environment at various times after a unilateral EC lesion. A–C, Twelve days after lesion, after 1 hr of exploration of a novel complex environment. D–F, Sixteen days after lesion, after 1 hr of exploration of a novel complex environment. G–I, Thirty days after lesion, after 1 hr of exploration of a novel complex environment. CA1 andCA3 indicate the respective subdivisions of the hippocampus proper. DG, Dentate gyrus.