Optimizing synaptic architecture and efficiency for high-frequency transmission.
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.
Taschenberger
Holger
H
The Vollum Institute, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97201, USA.
Leão
Ricardo M
RM
Rowland
Kevin C
KC
Spirou
George A
GA
von Gersdorff
Henrique
H
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000818:Animals; D000831:Animals, Newborn; D001306:Auditory Pathways / Q000254:growth & development* / Q000502:physiology / Q000648:ultrastructure; D001933:Brain Stem / Q000254:growth & development* / Q000502:physiology / Q000648:ultrastructure; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology*; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology; D005089:Exocytosis / Q000187:drug effects / Q000502:physiology; D018698:Glutamic Acid / Q000378:metabolism; D036881:Long-Term Synaptic Depression / Q000187:drug effects / Q000502:physiology; D008854:Microscopy, Electron; D017729:Presynaptic Terminals / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D051381:Rats; D017207:Rats, Sprague-Dawley; D018091:Receptors, AMPA / Q000187:drug effects / Q000502:physiology; D013570:Synaptic Membranes / Q000187:drug effects / Q000502:physiology / Q000648:ultrastructure; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology*; D013572:Synaptic Vesicles / Q000187:drug effects / Q000502:physiology / Q000648:ultrastructure
D018691:Excitatory Amino Acid Antagonists; D018091:Receptors, AMPA; D018698:Glutamic Acid