MemoryMemory, Short-TermMemory, Long-TermMemory DisordersImmunologic MemoryMemory, EpisodicMental RecallTime FactorsNeuropsychological TestsMaze LearningRetention (Psychology)Recognition (Psychology)HippocampusLearningAssociation LearningAmnesiaAnalysis of VarianceVerbal LearningFearCognitionSpatial BehaviorMagnetic Resonance ImagingReaction TimeTreatment OutcomeFollow-Up StudiesBrainAvoidance LearningConditioning (Psychology)Cognition DisordersCD8-Positive T-LymphocytesMice, Inbred C57BL