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Cereb Cortex. 2017 Mar 1;27(3):1779-1794. doi: 10.1093/cercor/bhw010.

Direct Visualization and Mapping of the Spatial Course of Fiber Tracts at Microscopic Resolution in the Human Hippocampus.

Author information

1
Department of Radiology, Stanford University, Lucas Center for Imaging, Stanford, CA 94305, USA.
2
Institute of Neuroscience and Medicine (INM-1), Research Centre Jülich, Jülich, Germany.
3
Institute of Anatomy, University of Rostock, Rostock, Germany.
4
Ahmanson-Lovelace Brain Mapping Center, David Geffen School of Medicine UCLA, Los Angeles, USA.
5
C. and O. Vogt Institute for Brain Research, Heinrich Heine University Düsseldorf, Düsseldorf, Germany.
6
Department of Psychiatry, Psychotherapy and Psychosomatics, RWTH Aachen University, Aachen, Germany.
7
JARA Jülich-Aachen Research Alliance, Translational Brain Medicine, Jülich, Germany.

Abstract

While hippocampal connectivity is essential to normal memory function, our knowledge of human hippocampal circuitry is largely inferred from animal studies. Using polarized light microscopy at 1.3 µm resolution, we have directly visualized the 3D course of key medial temporal pathways in 3 ex vivo human hemispheres and 2 ex vivo vervet monkey hemispheres. The multiple components of the perforant path system were clearly identified: Superficial sheets of fibers emanating from the entorhinal cortex project to the presubiculum and parasubiculum, intermixed transverse and longitudinal angular bundle fibers perforate the subiculum and then project to the cornu ammonis (CA) fields and dentate molecular layer, and a significant alvear component runs from the angular bundle to the CA fields. From the hilus, mossy fibers localize to regions of high kainate receptor density, and the endfolial pathway, mostly investigated in humans, merges with the Schaffer collaterals. This work defines human hippocampal pathways underlying mnemonic function at an unprecedented resolution.

KEYWORDS:

entorhinal cortex; hippocampus; human circuitry; perforant pathway; polarized light microscopy

PMID:
26874183
PMCID:
PMC5963820
DOI:
10.1093/cercor/bhw010
[Indexed for MEDLINE]
Free PMC Article

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