Augmentation Is a Potentiation of the Exocytotic Process

• Published in: Neuron (Cambridge, Mass.) Vol. 22; no. 1; pp. 139 - 146
• Main Authors: Stevens, Charles F, Wesseling, John F
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 1999
• Subjects: Action Potentials - physiology; Animals; Calcium - metabolism; Cells, Cultured; Chelating Agents - pharmacology; Egtazic Acid - pharmacology; Exocytosis - physiology; Intracellular Membranes - metabolism; Neurons - physiology; Neurotransmitter Agents - metabolism; Osmosis - drug effects; Presynaptic Terminals - physiology; Rats; Reaction Time - drug effects; Synapses - physiology
• ISSN: 0896-6273; 1097-4199
• DOI: 10.1016/S0896-6273(00)80685-6

Short-term synaptic enhancement is caused by an increase in the probability with which synaptic terminals release transmitter in response to presynaptic action potentials. Since exocytosed vesicles are drawn from a readily releasable pool of packaged transmitter, enhancement must result either from an increase in the size of the pool or an elevation in the fraction of releasable vesicles that undergoes exocytosis with each action potential. We show here that at least one major component of enhancement, augmentation, is not caused by an increase in the size of the readily releasable pool but is instead associated with an increase in the efficiency with which action potentials induce the exocytosis of readily releasable vesicles.