A international work, led by researchers from the Cajal Laboratory of Cortical Circuits of the Biomedical Technology Center of the Polytechnic University of Madrid (UPM), the Instituto Cajal, CSIC of the UPM, and of the National University of Distance Education (UNED), has mapped for the first time in three dimensions the neural connections of the hippocampus, thus advancing the understanding of the healthy brain and its alterations in pathologies.

Specifically, experts have provided the first detailed description from synaptic organization in this part of the brain. Using state-of-the-art electron microscopes and brain tissue samples obtained after the individual’s death, they have visualized almost 25,000 connections between neurons.

Specifically, their analysis showed that las sinapsis they were more densely packed in some layers of the hippocampus than others. Although many different types of connections were observed, most synapses were excitatory and established with the dendritic “spines”, microscopic structures that were discovered by Cajal.