Related Experiment Video
Updated: Mar 23, 2026
08:10
Examination of Synaptic Vesicle Recycling Using FM Dyes During Evoked, Spontaneous, and Miniature Synaptic Activities
Published on: March 31, 2014
21.7K
Counting Vesicular Release Events Reveals Binomial Release Statistics at Single Glutamatergic Synapses
Gerardo Malagon1, Takafumi Miki1, Isabel Llano1
1Laboratoire de Physiologie Cérébrale, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 8118, Université Paris Descartes, 75006 Paris, France, and.
Summary
Researchers quantified synaptic vesicle release at simple glutamatergic synapses, finding significant postsynaptic saturation and limited vesicle release per active zone, indicating both pre- and postsynaptic contributions to signal saturation.
Area of Science:
- Neuroscience
- Synaptic Physiology
- Molecular Neurobiology
Background:
- Central glutamatergic synapses typically feature a single presynaptic active zone and postsynaptic density.
- The functional properties of these
- simple synapses,
- particularly vesicle release per action potential, remain poorly understood.
Purpose of the Study:
- To develop and apply reliable methods for counting vesicular release at simple glutamatergic synapses.
- To investigate the contributions of presynaptic and postsynaptic mechanisms to signal saturation.
Main Methods:
- Extracellular stimulation of single parallel fibers in rat cerebellar slices.
- Deconvolution of excitatory postsynaptic currents (EPSCs) using quantal signals.
- Analysis of quantal amplitude occlusion and cumulative desensitization.
Main Results:
- Quantal amplitudes were reduced by 62% in consecutive EPSCs due to postsynaptic receptor saturation.
- Cumulative desensitization reduced subsequent EPSC amplitudes by approximately 3%.
- Vesicular release counts followed binomial statistics, with a maximum of 2-10 vesicles per synapse, reflecting docking site availability.
Conclusions:
- Postsynaptic saturation, driven by high receptor engagement (62%), is a major contributor to signal saturation at glutamatergic synapses.
- Presynaptic vesicle release is limited by the number of available docking sites at the active zone.
- Both presynaptic and postsynaptic factors contribute to signal saturation in individual glutamatergic synapses.
Related Concept Videos
01:26Fusion of Secretory Vesicles with the Plasma Membrane
19.3K
Proteins and neurotransmitters in secretory vesicles can be released from a cell upon vesicle docking, priming, and fusion with the plasma membrane. Vesicles are docked and primed in preparation for the quick exocytosis of their contents in response to a stimulus. The fusion process is mainly carried out by a SNAP Receptor or SNARE complex, consisting of synaptobrevin, syntaxin-1, and SNAP-25.
In 1993, Jim Rothman proposed that the antiparallel pairing of vesicular and transmembrane SNAREs, or...
In 1993, Jim Rothman proposed that the antiparallel pairing of vesicular and transmembrane SNAREs, or...
19.3K
01:28Integration of Synaptic Events
5.7K
Synaptic integration mainly includes the summation of graded potentials. Graded potentials, regardless of their type, cause subtle alterations in membrane voltage, resulting in either depolarization or hyperpolarization. These incremental changes, when combined or summed, can propel the neuron toward its threshold. Consider, for example, a membrane experiencing a +15 mV shift, causing it to depolarize from -70 mV to -55 mV. In this scenario, graded potentials govern the membrane's ability to...
5.7K
01:26Chemical Synapses
7.9K
Chemical synapses are specialized sites between two neurons or between a neuron and a non-neuronal cell like a muscle, glandular or sensory cell.
Because chemical synapses depend on the release of neurotransmitter molecules from synaptic vesicles to pass on their signal, there is an approximately one millisecond delay between when the axon potential reaches the presynaptic terminal and when the neurotransmitter leads to opening of postsynaptic ion channels. Additionally, this signaling is...
Because chemical synapses depend on the release of neurotransmitter molecules from synaptic vesicles to pass on their signal, there is an approximately one millisecond delay between when the axon potential reaches the presynaptic terminal and when the neurotransmitter leads to opening of postsynaptic ion channels. Additionally, this signaling is...
7.9K
01:26Chemical Synapses
12.4K
Chemical synapses are specialized sites between two neurons or between a neuron and a non-neuronal cell like a muscle, glandular or sensory cell.
Because chemical synapses depend on the release of neurotransmitter molecules from synaptic vesicles to pass on their signal, there is an approximately one millisecond delay between when the axon potential reaches the presynaptic terminal and when the neurotransmitter leads to opening of postsynaptic ion channels. Additionally, this signaling is...
Because chemical synapses depend on the release of neurotransmitter molecules from synaptic vesicles to pass on their signal, there is an approximately one millisecond delay between when the axon potential reaches the presynaptic terminal and when the neurotransmitter leads to opening of postsynaptic ion channels. Additionally, this signaling is...
12.4K
01:29Excitatory and Inhibitory Effects of Neurotransmitters
14.5K
When an action potential reaches the presynaptic axon terminal, it releases neurotransmitters from the neuron into the synaptic cleft at a chemical synapse. The released neurotransmitter can be excitatory or inhibitory. The critical criteria commonly used to determine whether a molecule is a neurotransmitter at a chemical synapse are the molecule's presence in the presynaptic neuron. Second, its release is in response to strong presynaptic depolarization. And lastly, the presence of...
14.5K
02:47The Synapse
137.2K
Neurons communicate with one another by passing on their electrical signals to other neurons. A synapse is the location where two neurons meet to exchange signals. At the synapse, the neuron that sends the signal is called the presynaptic cell, while the neuron that receives the message is called the postsynaptic cell. Note that most neurons can be both presynaptic and postsynaptic, as they both transmit and receive information.
137.2K