Mice, KnockoutPhenotypeMice, Inbred C57BLGene Knockout TechniquesMice, Inbred StrainsDisease Models, AnimalMice, TransgenicMice, Inbred BALB CSpleenAttention Deficit Disorder with HyperactivityMice, Mutant StrainsBrainMemory DisordersTime FactorsBehavior, AnimalCells, CulturedMaze LearningCognition DisordersMice, Inbred CBANeuropsychological TestsMice, Inbred C3HLiverRNA, MessengerLearning DisordersGene DeletionMice, Inbred DBA