Three-dimensional synaptic organization of the human hippocampal CA1 field

• DOI: 10.7554/elife.57013
• Publication Date: 2020-07-21T00:00:34Z
• Authors: Marta Montero-Crespo; Marta Dominguez-A...; Patricia Rondon-C...; Lidia Alonso-Nanc...; Javier DeFelipe; Lidia Blazquez-Ll...
• Keywords: Adult; Male; 0301 basic medicine; Medicina; microanatomy; QH301-705.5; Science; Molecular Conformation; 03 medical and health sciences; autopsy; 0302 clinical medicine; synapse; Cadaver; Humans; human; Biology (General); CA1 Region, Hippocampal; Aged; Aged, 80 and over; Q; R; dementia, electron microscopy, FIB/SEM, hippocampus, synapses; Middle Aged; 16. Peace & justice; FIB/SEM microscopy; 3. Good health; Microscopy, Electron, Scanning; Medicine; Female; Autopsy; Neuroscience

The hippocampal CA1 field integrates a wide variety of subcortical and cortical inputs, but its synaptic organization in humans is still unknown due to the difficulties involved studying the human brain via electron microscope techniques. However, we have shown that the 3D reconstruction method using Focused Ion Beam/Scanning Electron Microscopy (FIB/SEM) can be applied to study in detail the synaptic organization of the human brain obtained from autopsies, yielding excellent results. Using this technology, 24,752 synapses were fully reconstructed in CA1, revealing that most of them were excitatory, targeting dendritic spines and displaying a macular shape, regardless of the layer examined. However, remarkable differences were observed between layers. These data constitute the first extensive description of the synaptic organization of the neuropil of the human CA1 region.