Volume electron microscopy reveals unique laminar synaptic characteristics in the human entorhinal cortex
- Instituto Cajal (CSIC), Spain
Abstract
The entorhinal cortex (EC) plays a pivotal role in memory function and spatial navigation, connecting the hippocampus with the neocortex. The EC integrates a wide range of cortical and subcortical inputs, but its synaptic organization in the human brain is largely unknown. We used volume electron microscopy to perform a 3D analysis of the microanatomical features of synapses in all layers of the medial EC (MEC) from the human brain. Using this technology, 12,974 synapses were fully 3D reconstructed at the ultrastructural level. The MEC presented a distinct set of synaptic features, differentiating this region from other human cortical areas. Furthermore, ultrastructural synaptic characteristics within the MEC was predominantly similar, although layers I and VI exhibited several synaptic characteristics that were distinct from other layers. The present study constitutes an extensive description of the synaptic characteristics of the neuropil of all layers of the EC, a crucial step to better understand the connectivity of this cortical region, in both health and disease.
Data availability
Most data are available in the main text or the supplementary files. Raw data used for analysis are provided in Supplementary File 4.Stack of images are available at BossDB.org as project page:https://10.60533/boss-2024-ekc7The datasets used and analyzed during the current study are published in the EBRAINS Knowledge Graph:https://doi.org/10.25493/3GMJ-FEZhttps://doi.org/10.25493/QGH8-MTShttps://doi.org/10.25493/CSB1-Q07
Article and author information
Author details
Lidia Alonso-Nanclares
Funding
Ministerio de Ciencia e Innovación (PID2021-127924NB-I00)
- Javier DeFelipe
CSIC Interdisciplinary Thematic Platform (Cajal Blue Brain)
- Javier DeFelipe
European Union's Horizon 2020 Framework Programme for Research and Innovation (Grant Agreement No. 945539 (Human Brain Project SGA3))
- Javier DeFelipe
Ministerio de Ciencia e Innovación (PRE2019-089228)
- Nicolas Cano-Astorga
Ministerio de Ciencia, Innovación y Universidades (FPU19/00007)
- Sergio Plaza-Alonso
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Ethics
Human subjects: Human brain tissue was obtained from 3 autopsies with no recorded neurological or psychiatric alterations (supplied by Unidad Asociada Neuromax, Laboratorio de Neuroanatomía Humana, Facultad de Medicina, Universidad de Castilla-La Mancha, Albacete, Spain). The consent of the individuals was obtained and the sampling procedure was approved by the Institutional Ethical Committee of the Albacete University Hospital. The tissue was obtained following national laws and international ethical and technical guidelines on the use of human samples for biomedical research purposes. Human brain tissue from the same subjects has been used in previous studies (Cano-Astorga et al., 2021, 2023; Domínguez-Álvaro et al., 2021a; Montero-Crespo et al., 2020).
Copyright
© 2025, Plaza-Alonso et al.
This article is distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use and redistribution provided that the original author and source are credited.
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