Study of the Size and Shape of Synapses in the Juvenile Rat Somatosensory Cortex with 3D Electron Microscopy

Changes in the size of the synaptic junction are thought to have significant functional consequences. We used focused ion beam milling and scanning electron microscopy (FIB/SEM) to obtain stacks of serial sections from the six layers of the rat somatosensory cortex. We have segmented in 3D a large n...

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Bibliographic Details
Published in:eNeuro 2018-01, Vol.5 (1), p.ENEURO.0377-17.2017
Main Authors: Santuy, Andrea, Rodríguez, José-Rodrigo, DeFelipe, Javier, Merchán-Pérez, Angel
Format: Article
Language:English
Subjects:
Animals
Imaging, Three-Dimensional
Male
Microscopy, Electron, Scanning - methods
Neural Inhibition
New Research
Pattern Recognition, Automated
Rats, Wistar
Software
Somatosensory Cortex - cytology
Somatosensory Cortex - growth & development
Synapses
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Summary:Changes in the size of the synaptic junction are thought to have significant functional consequences. We used focused ion beam milling and scanning electron microscopy (FIB/SEM) to obtain stacks of serial sections from the six layers of the rat somatosensory cortex. We have segmented in 3D a large number of synapses ( = 6891) to analyze the size and shape of excitatory (asymmetric) and inhibitory (symmetric) synapses, using dedicated software. This study provided three main findings. Firstly, the mean synaptic sizes were smaller for asymmetric than for symmetric synapses in all cortical layers. In all cases, synaptic junction sizes followed a log-normal distribution. Secondly, most cortical synapses had disc-shaped postsynaptic densities (PSDs; 93%). A few were perforated (4.5%), while a smaller proportion (2.5%) showed a tortuous horseshoe-shaped perimeter. Thirdly, the curvature was larger for symmetric than for asymmetric synapses in all layers. However, there was no correlation between synaptic area and curvature.
ISSN:2373-2822
2373-2822
DOI:10.1523/ENEURO.0377-17.2017