Biology subjects

Montero-Crespo, M.

Publications and source records attributed to Montero-Crespo, M..

3 recordsLinked to original sources

bioRxiv2020

3D ultrastructural study of synapses in the human entorhinal cortex

The entorhinal cortex (EC) is a brain region that has been shown to be essential for memory functions and spatial navigation. However, detailed 3D synaptic morphology analysis and identification of postsynaptic targets at the ultrastructural level have not been performed before in the human EC. In the present study, we used Focused Ion Beam/Scanning Electron Microscopy (FIB/SEM) to perform a three-dimensional analysis of the synapses in the neuropil of medial EC in layers II and III from human brain autopsies. Specifically, we studied synaptic structural parameters of 3561 synapses, 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, the postsynaptic targets of synapses could be clearly determined. The present work constitutes a detailed description of the synaptic organization of the human EC, which is a necessary step to better understand the functional organization of this region in both health and disease. Significance StatementThe present study represents the first attempt to unveil the detailed synaptic organization of the neuropil of the human entorhinal cortex -- a brain region that is essential for memory function and spatial navigation. Using 3D electron microscopy, we have characterized the synaptic morphology and identified the postsynaptic targets of thousands of synapses. The results provide a new, large, quantitative ultrastructure dataset of the synaptic organization of the human entorhinal cortex. These data provide critical information to better understand synaptic functionality in the human brain. HighlightEstimation of the number of synapses, as well as determination of their type, shapes, sizes and postsynaptic targets, provides critical data to better understand synaptic functionality. This study provides a new, large, quantitative ultrastructure dataset of the synaptic organization of the human entorhinal cortex using 3D electron microscopy.

neuroscience↗

bioRxiv2020

3D SYNAPTIC ORGANIZATION OF THE RAT CA1 AND ALTERATIONS INDUCED BY COCAINE SELF-ADMINISTRATION

The hippocampus plays a key role in contextual conditioning and has been proposed as an important component of the cocaine addiction brain circuit. To gain knowledge about cocaine-induced alterations in this circuit, we used Focused Ion Beam milling/Scanning Electron Microscopy (FIB/SEM) to reveal and quantify the 3D synaptic organization of the stratum radiatum of rat CA1, under normal circumstances and after cocaine-self administration (SA). Most synapses are asymmetric (excitatory), macular-shaped, and in contact with spine heads. After cocaine-SA, the size and complexity of both asymmetric and symmetric (inhibitory) synapses increased but no changes were observed in the synaptic density. This work constitutes the first detailed report on the 3D synaptic organization in the stratum radiatum of the CA1 field of cocaine-SA rats. Our data contribute to the elucidation of the normal and altered synaptic organization of the hippocampus, which is crucial for better understanding the neurobiological mechanisms underlying cocaine addiction.

neuroscience↗

bioRxiv2020

Three-dimensional synaptic organization of the human hippocampal CA1 field

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.

neuroscience↗