Amygdala/metabolism; Membrane Potentials/physiology; Neural Inhibition/physiology; Neural Pathways/metabolism; Neurons/metabolism; Receptors, N-Methyl-D-Aspartate/metabolism; Synapses/metabolism; Action Potentials/drug effects; Action Potentials/physiology; Amygdala/cytology; Amygdala/drug effects; Animals; GABA-A Receptor Antagonists; Guinea Pigs; Interneurons/cytology; Interneurons/drug effects; Interneurons/metabolism; Membrane Potentials/drug effects; N-Methylaspartate/pharmacology; Neural Inhibition/drug effects; Neural Pathways/cytology; Neural Pathways/drug effects; Neurons/cytology; Neurons/drug effects; Organ Culture Techniques; Receptors, GABA-A/metabolism; Receptors, Glycine/antagonists & inhibitors; Receptors, Glycine/metabolism; Receptors, N-Methyl-D-Aspartate/agonists; Receptors, N-Methyl-D-Aspartate/antagonists & inhibitors; Synapses/drug effects; Synapses/ultrastructure; Tetrodotoxin/pharmacology; gamma-Aminobutyric Acid/metabolism