Gene Expression Regulation, Developmental/physiology; Glutamic Acid/metabolism; Neurons/physiology; Receptors, Nicotinic/physiology; Synapses/physiology; Age Factors; Analysis of Variance; Animals; Animals, Newborn; Cells, Cultured; Disks Large Homolog 4 Protein; Electric Stimulation; Embryo, Mammalian; Excitatory Postsynaptic Potentials/drug effects; Excitatory Postsynaptic Potentials/genetics; Female; GABA Antagonists/pharmacology; Gene Expression Regulation, Developmental/drug effects; Gene Expression Regulation, Developmental/genetics; Green Fluorescent Proteins/genetics; Green Fluorescent Proteins/metabolism; Guanylate Kinases/metabolism; Hippocampus/cytology; Male; Membrane Proteins/metabolism; Mice; Mice, Inbred C57BL; Mice, Knockout; Microscopy, Electron, Transmission; Neurites/metabolism; Neurites/ultrastructure; Neurons/drug effects; Neurons/ultrastructure; Nicotine/pharmacology; Nicotinic Agonists/pharmacology; Organ Culture Techniques; Patch-Clamp Techniques; Pyridazines/pharmacology; Pyridinium Compounds; Quaternary Ammonium Compounds; RNA, Small Interfering/genetics; RNA, Small Interfering/metabolism; Rats; Receptors, AMPA/metabolism; Receptors, Nicotinic/deficiency; Receptors, Nicotinic/genetics; Sodium Channel Blockers/pharmacology; Synapses/ultrastructure; Tetrodotoxin/pharmacology; Time Factors; Transduction, Genetic/methods; Vesicular Glutamate Transport Protein 1/metabolism; Visual Cortex/cytology; Visual Cortex/metabolism; alpha7 Nicotinic Acetylcholine Receptor