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The Mossy Fiber Bouton: the “Common” or the “Unique” Synapse?

Synapses are the key elements for signal processing and plasticity in the brain. They are composed of nearly the same structural subelements, an apposition zone including a pre- and postsynaptic density, a cleft and a pool of vesicles. It is, however, their actual composition that determines their d...

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Autores principales: Rollenhagen, Astrid, Lübke, Joachim H. R.
Formato: Texto
Lenguaje:English
Publicado: Frontiers Research Foundation 2010
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3059708/
https://www.ncbi.nlm.nih.gov/pubmed/21423488
http://dx.doi.org/10.3389/fnsyn.2010.00002
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author Rollenhagen, Astrid
Lübke, Joachim H. R.
author_facet Rollenhagen, Astrid
Lübke, Joachim H. R.
author_sort Rollenhagen, Astrid
collection PubMed
description Synapses are the key elements for signal processing and plasticity in the brain. They are composed of nearly the same structural subelements, an apposition zone including a pre- and postsynaptic density, a cleft and a pool of vesicles. It is, however, their actual composition that determines their different behavior in synaptic transmission and plasticity. Here, we describe and discuss the structural factors underlying the unique functional properties of the hippocampal mossy fiber (MF) synapse. Two membrane specializations, active zones (AZs; transmitter release sites), and puncta adherentia (PA), putative adhesion complexes were found. On average, individual boutons had ∼20 AZs with a mean surface area of 0.1 μm(2) and a short distance of 0.45 μm between individual AZs. Mossy fiber boutons (MFBs) and their target structures were isolated from each other by astrocytes, but fine glial processes never reached the AZs. Therefore, two structural factors are likely to promote synaptic cross-talk: the short distance and the absence of fine glial processes between individual AZs. Thus, synaptic crosstalk may contribute to the high efficacy of hippocampal MF synapses. On average, an adult bouton contained ∼16,000 synaptic vesicles; ∼600 vesicles were located within 60 nm from the AZ, ∼4000 between 60 nm and 200 nm, and the remaining beyond 200 nm, suggesting large readily releasable, recycling, and reserve pools. Thus, the size of the three pools together with the number and distribution of AZs underlie the unique extent of synaptic efficacy and plasticity of the hippocampal MF synapse.
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spelling pubmed-30597082011-03-21 The Mossy Fiber Bouton: the “Common” or the “Unique” Synapse? Rollenhagen, Astrid Lübke, Joachim H. R. Front Synaptic Neurosci Neuroscience Synapses are the key elements for signal processing and plasticity in the brain. They are composed of nearly the same structural subelements, an apposition zone including a pre- and postsynaptic density, a cleft and a pool of vesicles. It is, however, their actual composition that determines their different behavior in synaptic transmission and plasticity. Here, we describe and discuss the structural factors underlying the unique functional properties of the hippocampal mossy fiber (MF) synapse. Two membrane specializations, active zones (AZs; transmitter release sites), and puncta adherentia (PA), putative adhesion complexes were found. On average, individual boutons had ∼20 AZs with a mean surface area of 0.1 μm(2) and a short distance of 0.45 μm between individual AZs. Mossy fiber boutons (MFBs) and their target structures were isolated from each other by astrocytes, but fine glial processes never reached the AZs. Therefore, two structural factors are likely to promote synaptic cross-talk: the short distance and the absence of fine glial processes between individual AZs. Thus, synaptic crosstalk may contribute to the high efficacy of hippocampal MF synapses. On average, an adult bouton contained ∼16,000 synaptic vesicles; ∼600 vesicles were located within 60 nm from the AZ, ∼4000 between 60 nm and 200 nm, and the remaining beyond 200 nm, suggesting large readily releasable, recycling, and reserve pools. Thus, the size of the three pools together with the number and distribution of AZs underlie the unique extent of synaptic efficacy and plasticity of the hippocampal MF synapse. Frontiers Research Foundation 2010-03-15 /pmc/articles/PMC3059708/ /pubmed/21423488 http://dx.doi.org/10.3389/fnsyn.2010.00002 Text en Copyright © 2010 Rollenhagen and Lübke. http://www.frontiersin.org/licenseagreement This is an open-access article subject to an exclusive license agreement between the authors and the Frontiers Research Foundation, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are credited.
spellingShingle Neuroscience
Rollenhagen, Astrid
Lübke, Joachim H. R.
The Mossy Fiber Bouton: the “Common” or the “Unique” Synapse?
title The Mossy Fiber Bouton: the “Common” or the “Unique” Synapse?
title_full The Mossy Fiber Bouton: the “Common” or the “Unique” Synapse?
title_fullStr The Mossy Fiber Bouton: the “Common” or the “Unique” Synapse?
title_full_unstemmed The Mossy Fiber Bouton: the “Common” or the “Unique” Synapse?
title_short The Mossy Fiber Bouton: the “Common” or the “Unique” Synapse?
title_sort mossy fiber bouton: the “common” or the “unique” synapse?
topic Neuroscience
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3059708/
https://www.ncbi.nlm.nih.gov/pubmed/21423488
http://dx.doi.org/10.3389/fnsyn.2010.00002
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