Optimizing Synaptic Architecture and Efficiency for High-Frequency Transmission

• Published in: Neuron (Cambridge, Mass.) Mass.), 2002-12, Vol.36 (6), p.1127-1143
• Main Authors: Taschenberger, Holger, Leão, Ricardo M., Rowland, Kevin C., Spirou, George A., von Gersdorff, Henrique
• Format: Article
• Language: English
• Subjects: Action Potentials - drug effects; Action Potentials - physiology; Animals; Animals, Newborn; Architecture; Auditory Pathways - growth & development; Auditory Pathways - physiology; Auditory Pathways - ultrastructure; Brain Stem - growth & development; Brain Stem - physiology; Brain Stem - ultrastructure; Calcium Signaling - drug effects; Calcium Signaling - physiology; Cell Differentiation - drug effects; Cell Differentiation - physiology; Efficiency; Excitatory Amino Acid Antagonists - pharmacology; Excitatory Postsynaptic Potentials - drug effects; Excitatory Postsynaptic Potentials - physiology; Exocytosis - drug effects; Exocytosis - physiology; Glutamic Acid - metabolism; Long-Term Synaptic Depression - drug effects; Long-Term Synaptic Depression - physiology; Microscopy, Electron; Presynaptic Terminals - drug effects; Presynaptic Terminals - physiology; Presynaptic Terminals - ultrastructure; Rats; Rats, Sprague-Dawley; Receptors, AMPA - drug effects; Receptors, AMPA - physiology; Rodents; Synaptic Membranes - drug effects; Synaptic Membranes - physiology; Synaptic Membranes - ultrastructure; Synaptic Transmission - drug effects; Synaptic Transmission - physiology; Synaptic Vesicles - drug effects; Synaptic Vesicles - physiology; Synaptic Vesicles - ultrastructure
• ISSN: 0896-6273; 1097-4199
• DOI: 10.1016/S0896-6273(02)01137-6

Bursts of neuronal activity are transmitted more effectively as synapses mature. However, the mechanisms that control synaptic efficiency during development are poorly understood. Here, we study postnatal changes in synaptic ultrastructure and exocytosis in a calyx-type nerve terminal. Vesicle pool size, exocytotic efficiency (amount of exocytosis per Ca influx), Ca current facilitation, and the number of active zones (AZs) increased with age, whereas AZ area, number of docked vesicles per AZ, and release probability decreased with age. These changes led to AZs that are less prone to multivesicular release, resulting in reduced AMPA receptor saturation and desensitization. A greater multiplicity of small AZs with few docked vesicles, a larger pool of releasable vesicles, and a higher efficiency of release thus promote prolonged high-frequency firing in mature synapses.