Ultrastructural heterogeneity of layer 4 excitatory synaptic boutons in the adult human temporal lobe neocortex.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 31746736.
- Also identified by DOI 10.7554/eLife.48373 and PMC identifier 6919978.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
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 μm<sup>2</sup>), with a single AZ (~0.13 µm<sup>2</sup>); 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.
Medical subject headings
- Neocortex
- Synapses
- Synaptic Vesicles
- Temporal Lobe