3D ultrastructural study of synapses using FIB/SEM in Human Primary Cortex (Brodmann areas 3b, 4 and 17) (v1.0)

We used Focused Ion Beam/Scanning Electron Microscopy (FIB/SEM) to perform a 3D analysis of the synapses in the layer III neuropils of the Brodmann areas 3b (somatosensory), 4 (motor), and 17 (visual primary) from human brain samples. 3 human brain autopsies cases have been used to achieve a total of 22 FIB/SEM valid image stacks: 4 stacks in BA17 from a single case (AB7); 9 stacks in BA3b (three stacks per case, AB2, AB3, and AB7); and 9 stacks in BA4 (three stacks per case, AB2, AB3, and AB7).
Specifically, we studied synaptic junctions, which were fully reconstructed in 3D. We analyzed the synaptic density, 3D spatial distribution, and type (excitatory and inhibitory), as well as the shape and size of each synaptic junction. Moreover, their postsynaptic targets were determined.
The present dataset constitutes a detailed description of the synaptic characteristics of the human cortex, which is a necessary step to better understand the organization of the cortex.