Exploratory and Locomotor Activity in Mice Following Selective Lesions of the Hippocampus: Effects of Lesion Site and Open Field Arena Size

The present study showed arena size-dependent effects on theimpairment of locomotor activity and rearing after lesions of caudalhippocampus in C57BL/6 mice: intensive high-speed locomotion withoutintra- and intertrial habituation accompanied by a decreased numberof rears and a reduced tortuosity of the route, suggesting significantimpairments of exploratory behavior in an unfamiliar large environment.The lesions of the rostral hippocampus resulted in slight hyperactivityin the large arena without impairment of habituation or rearing.The caudal hippocampus is thus crucial for the environment-dependentmodifications of exploratory behavior. Changes on exploratory behaviorafter its lesions are similar to ones following more extensive or completelesions of the hippocampus.