Synapses are fundamental building blocks controlling and modulating the 'behavior' of brain networks. How their structural composition, most notably their quantitative morphology underlie their computational properties remains rather unclear, particularly in humans. Here, excitatory synaptic boutons (SBs) in layer 4 (L4) of the temporal lobe neocortex (TLN) were quantitatively investigated. Biopsies from epilepsy surgery were used for fine-scale and tomographic electron microscopy (EM) to generate 3D-reconstructions of SBs. Particularly, the size of active zones (AZs) and that of the three functionally defined pools of synaptic vesicles (SVs) were quantified. SBs were comparatively small (~2.50 μm2), with a single AZ (~0.13 µm2); preferentially established on spines. SBs had a total pool of ~1800 SVs with strikingly large readily releasable (~ 20), recycling (~ 80) and resting pools (~850). Thus, human L4 SBs may act as 'amplifiers' of signals from the sensory periphery, integrate, synchronize and modulate intra- and extracortical synaptic activity.
Original datasets were already uploaded as source files since there is no appropriate domain-specific archive for our data.
- Rachida Yakoubi
- Joachim HR Lübke
- Joachim HR Lübke
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Human subjects: The consent of the patients was obtained and all experimental procedures were approved by the Ethical Committees of the Rheinische Friedrich-Wilhelms-University/University Hospital Bonn (ethic votum of the Medical Faculty to Prof. Dr. med. Johannes Schramm and Prof. Dr. rer. nat. Joachim Lübke, Nr. 146/11), and the University of Bochum (ethic votum of the Medical Faculty to PD Dr. med. Marec von Lehe and Prof. Dr. rer. nat. Joachim Lübke, Reg. No. 5190-14-15; ethic votum of the Medical Faculty to Dr. med. Dorothea Miller and Prof. Dr. rer. nat. Joachim Lübke, Reg. No. 17-6199-BR), and the EU directive (2015/565/EC and 2015/566/EC) concerning working with human tissue.
- Moritz Helmstaedter, Max Planck Institute for Brain Research, Germany
© 2019, Yakoubi et al.
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