Basic Helix-Loop-Helix Transcription Factors/metabolism; Cell Differentiation/genetics; Gene Expression Regulation, Developmental/physiology; Homeodomain Proteins/metabolism; NFI Transcription Factors/physiology; Stem Cells/physiology; Telencephalon/cytology; Age Factors; Analysis of Variance; Animals; Basic Helix-Loop-Helix Transcription Factors/genetics; Bromodeoxyuridine/metabolism; Cell Count/methods; Cerebral Ventricles/cytology; Cerebral Ventricles/embryology; Chromatin Immunoprecipitation/methods; Electrophoretic Mobility Shift Assay/methods; Embryo, Mammalian; Gene Expression Regulation, Developmental/genetics; Hippocampus/cytology; Hippocampus/growth & development; Homeodomain Proteins/genetics; Mice; Mice, Inbred C57BL; Mice, Knockout; Microarray Analysis/methods; Mutation/genetics; NFI Transcription Factors/deficiency; Nerve Tissue Proteins/genetics; Nerve Tissue Proteins/metabolism; Octamer Transcription Factor-6/genetics; Octamer Transcription Factor-6/metabolism; Promoter Regions, Genetic/physiology; Receptors, Kainic Acid/genetics; Receptors, Kainic Acid/metabolism; Telencephalon/embryology; Transcription Factor HES-1; Tumor Suppressor Proteins/genetics; Tumor Suppressor Proteins/metabolism