Phosphatidylinositol Phosphates/metabolism; Pyramidal Cells/cytology; Receptors, AMPA/metabolism; Synapses/physiology; Synaptic Transmission/physiology; Animals; Animals, Newborn; Calcium-Calmodulin-Dependent Protein Kinase Type 2/genetics; Calcium-Calmodulin-Dependent Protein Kinase Type 2/metabolism; Carrier Proteins/genetics; Dendrites/metabolism; Dendrites/ultrastructure; Dendritic Spines/metabolism; Dendritic Spines/ultrastructure; Disks Large Homolog 4 Protein; Enzyme Inhibitors/pharmacology; Excitatory Postsynaptic Potentials/drug effects; Excitatory Postsynaptic Potentials/physiology; Green Fluorescent Proteins/genetics; Hippocampus/cytology; Immunoprecipitation; Intracellular Signaling Peptides and Proteins/metabolism; Long-Term Potentiation/drug effects; Long-Term Potentiation/physiology; Membrane Proteins/metabolism; Microscopy, Immunoelectron/methods; Mutagenesis, Site-Directed/methods; Nerve Tissue Proteins/genetics; Organ Culture Techniques; Patch-Clamp Techniques/methods; Phosphatidylinositol 3-Kinases/physiology; Phosphatidylinositols/metabolism; Phosphoinositide-3 Kinase Inhibitors; Presynaptic Terminals/physiology; Presynaptic Terminals/ultrastructure; Protein Binding; Protein Transport/drug effects; Protein Transport/physiology; Pyramidal Cells/ultrastructure; Rats; Receptors, AMPA/genetics; Synapses/drug effects; Synapses/ultrastructure; Synaptic Transmission/drug effects; Time Factors; Transfection/methods