A synapse is the junction between two neurons that allows a signal to pass between them. Neurons are cells that transmit information between your brain and other parts of the central nervous system. Synapses are found where neurons connect with other neurons.
Synapses are key to thebrain’s function, especially when it comes tomemory.
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Function of Synapses
Synapses connect neurons and help transmit information from one neuron to the next. They pass sensory signals such as pain or touch from the nervous system to the brain, and they help you move the muscles in your body.They are also involved in memory processing and storage.
Types
There are two main types of synapses:
Chemical Synapses
In a chemical synapse, the electrical activity in the presynaptic neuron triggers the release of chemical messengers, the neurotransmitters. Most synapses are chemical.
The neurotransmitters diffuse across the synapse and bind to the specialized receptors of the postsynaptic cell.
The neurotransmitter then either excites or inhibits the postsynaptic neuron. Excitation leads to the firing of an electrical impulse known as an action potential, while inhibition prevents the propagation of a signal.
Chemical synapses are composed of three main parts:
Electrical Synapses
Electrical synapses allow electrical signals to travel quickly from the presynaptic cell to the postsynaptic cell, rapidly speeding up the transfer of signals.
The special protein channels that connect the two cells make it possible for the positive current from the presynaptic neuron to flow directly into the postsynaptic cell.
Think of the nerve signal like the electrical current, and the neurons like wires. Synapses would be the outlets or junction boxes that connect the current to a lamp (or other electrical appliance of your choosing), allowing the lamp to light.
Comparing the Types
Chemical SynapsesGap between: 20 nanometersSpeed: Several millisecondsNo loss of signal strengthExcitatory or inhibitoryElectrical SynapsesGap between: 3.5 nanometersSpeed: Nearly instantaneousSignal strength diminishesExcitatory only
Chemical SynapsesGap between: 20 nanometersSpeed: Several millisecondsNo loss of signal strengthExcitatory or inhibitory
Gap between: 20 nanometers
Speed: Several milliseconds
No loss of signal strength
Excitatory or inhibitory
Electrical SynapsesGap between: 3.5 nanometersSpeed: Nearly instantaneousSignal strength diminishesExcitatory only
Gap between: 3.5 nanometers
Speed: Nearly instantaneous
Signal strength diminishes
Excitatory only
The gap between electrical synapses is much smaller than that of a chemical synapse (about 3.5 nanometerscompared to 20 nanometers).
Electrical synapses transfer signals much faster than chemical synapses.While the speed of transmission in chemical synapses can take up to several milliseconds, the transmission at electrical synapses is nearly instantaneous.
While electrical synapses have the advantage of speed, the strength of a signal diminishes as it travels from one cell to the next. Because of this loss of signal strength, it requires a very large presynaptic neuron to influence much smaller postsynaptic neurons.
Chemical synapses may be slower, but they can transmit a message without any loss in signal strength. Very small presynaptic neurons are also able to influence even very large postsynaptic cells.
Where chemical synapses can be excitatory or inhibitory, electrical synapses are excitatory only.
Summary
A synapse is the junction that allows the signal to pass between neurons, which are cells that transmit information to and from your brain and yourcentral nervous system.
There are two main types of synapses: chemical and electrical. Electrical synapses transmit signals faster than chemical synapses, but chemical synapses transmit messages without any loss of signal strength.
9 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Abraham WC, Jones OD, Glanzman DL.Is plasticity of synapses the mechanism of long-term memory storage?NPJ Sci Learn. 2019;4:9. doi:10.1038/s41539-019-0048-yTexas A&M.How do synapses work?Langille JJ, Brown RE.The synaptic theory of memory: A historical survey and reconciliation of recent opposition.Front Syst Neurosci. 2018;12:52. doi:10.3389/fnsys.2018.00052Jabeen S, Thirumalai V.The interplay between electrical and chemical synaptogenesis.J Neurophysiol. 2018;120(4):1914-1922. doi:10.1152/jn.00398.2018Protachevicz PR, Batista AM, Caldas IL, Baptista MS.Analytical solutions for the short-term plasticity.Chaos Solit Fractals. 2024;181:114678. doi:10.1101/2023.04.03.535315Cole AA, Reese TS.Transsynaptic assemblies link domains of presynaptic and postsynaptic intracellular structures across the synaptic cleft.J Neurosci. 2023;43(33):5883-5892. doi:10.1523/JNEUROSCI.2195-22.2023Spray DC, Hanani M.Gap junctions, pannexins and pain.Neurosci Lett. 2019;695:46-52. doi:10.1016/j.neulet.2017.06.035Pekker M, Shneider MN.Physical model of electrical synapses in a neural network.bioRxiv. 2021:2021-12. doi:10.1101/2021.12.13.472453Connors BW.Synchrony and so much more: Diverse roles for electrical synapses in neural circuits.Dev Neurobiol. 2017;77(5):610-624. doi:10.1002/dneu.22493
9 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Abraham WC, Jones OD, Glanzman DL.Is plasticity of synapses the mechanism of long-term memory storage?NPJ Sci Learn. 2019;4:9. doi:10.1038/s41539-019-0048-yTexas A&M.How do synapses work?Langille JJ, Brown RE.The synaptic theory of memory: A historical survey and reconciliation of recent opposition.Front Syst Neurosci. 2018;12:52. doi:10.3389/fnsys.2018.00052Jabeen S, Thirumalai V.The interplay between electrical and chemical synaptogenesis.J Neurophysiol. 2018;120(4):1914-1922. doi:10.1152/jn.00398.2018Protachevicz PR, Batista AM, Caldas IL, Baptista MS.Analytical solutions for the short-term plasticity.Chaos Solit Fractals. 2024;181:114678. doi:10.1101/2023.04.03.535315Cole AA, Reese TS.Transsynaptic assemblies link domains of presynaptic and postsynaptic intracellular structures across the synaptic cleft.J Neurosci. 2023;43(33):5883-5892. doi:10.1523/JNEUROSCI.2195-22.2023Spray DC, Hanani M.Gap junctions, pannexins and pain.Neurosci Lett. 2019;695:46-52. doi:10.1016/j.neulet.2017.06.035Pekker M, Shneider MN.Physical model of electrical synapses in a neural network.bioRxiv. 2021:2021-12. doi:10.1101/2021.12.13.472453Connors BW.Synchrony and so much more: Diverse roles for electrical synapses in neural circuits.Dev Neurobiol. 2017;77(5):610-624. doi:10.1002/dneu.22493
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
Abraham WC, Jones OD, Glanzman DL.Is plasticity of synapses the mechanism of long-term memory storage?NPJ Sci Learn. 2019;4:9. doi:10.1038/s41539-019-0048-yTexas A&M.How do synapses work?Langille JJ, Brown RE.The synaptic theory of memory: A historical survey and reconciliation of recent opposition.Front Syst Neurosci. 2018;12:52. doi:10.3389/fnsys.2018.00052Jabeen S, Thirumalai V.The interplay between electrical and chemical synaptogenesis.J Neurophysiol. 2018;120(4):1914-1922. doi:10.1152/jn.00398.2018Protachevicz PR, Batista AM, Caldas IL, Baptista MS.Analytical solutions for the short-term plasticity.Chaos Solit Fractals. 2024;181:114678. doi:10.1101/2023.04.03.535315Cole AA, Reese TS.Transsynaptic assemblies link domains of presynaptic and postsynaptic intracellular structures across the synaptic cleft.J Neurosci. 2023;43(33):5883-5892. doi:10.1523/JNEUROSCI.2195-22.2023Spray DC, Hanani M.Gap junctions, pannexins and pain.Neurosci Lett. 2019;695:46-52. doi:10.1016/j.neulet.2017.06.035Pekker M, Shneider MN.Physical model of electrical synapses in a neural network.bioRxiv. 2021:2021-12. doi:10.1101/2021.12.13.472453Connors BW.Synchrony and so much more: Diverse roles for electrical synapses in neural circuits.Dev Neurobiol. 2017;77(5):610-624. doi:10.1002/dneu.22493
Abraham WC, Jones OD, Glanzman DL.Is plasticity of synapses the mechanism of long-term memory storage?NPJ Sci Learn. 2019;4:9. doi:10.1038/s41539-019-0048-y
Texas A&M.How do synapses work?
Langille JJ, Brown RE.The synaptic theory of memory: A historical survey and reconciliation of recent opposition.Front Syst Neurosci. 2018;12:52. doi:10.3389/fnsys.2018.00052
Jabeen S, Thirumalai V.The interplay between electrical and chemical synaptogenesis.J Neurophysiol. 2018;120(4):1914-1922. doi:10.1152/jn.00398.2018
Protachevicz PR, Batista AM, Caldas IL, Baptista MS.Analytical solutions for the short-term plasticity.Chaos Solit Fractals. 2024;181:114678. doi:10.1101/2023.04.03.535315
Cole AA, Reese TS.Transsynaptic assemblies link domains of presynaptic and postsynaptic intracellular structures across the synaptic cleft.J Neurosci. 2023;43(33):5883-5892. doi:10.1523/JNEUROSCI.2195-22.2023
Spray DC, Hanani M.Gap junctions, pannexins and pain.Neurosci Lett. 2019;695:46-52. doi:10.1016/j.neulet.2017.06.035
Pekker M, Shneider MN.Physical model of electrical synapses in a neural network.bioRxiv. 2021:2021-12. doi:10.1101/2021.12.13.472453
Connors BW.Synchrony and so much more: Diverse roles for electrical synapses in neural circuits.Dev Neurobiol. 2017;77(5):610-624. doi:10.1002/dneu.22493
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