title: Direct Visualization and Mapping of the Spatial Course of Fiber Tracts at Microscopic Resolution in the Human Hippocampus.
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.
authors.affiliation: Department of Radiology, Stanford University, Lucas Center for Imaging, Stanford, CA 94305, USA.
authors.forename: Michael M
authors.initials: MM
authors.lastname: Zeineh
authors.affiliation: Institute of Neuroscience and Medicine (INM-1), Research Centre Jülich, Jülich, Germany.
authors.forename: Nicola
authors.initials: N
authors.lastname: Palomero-Gallagher
authors.affiliation: Institute of Neuroscience and Medicine (INM-1), Research Centre Jülich, Jülich, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Axer
authors.affiliation: Institute of Neuroscience and Medicine (INM-1), Research Centre Jülich, Jülich, Germany.
authors.forename: David
authors.initials: D
authors.lastname: Gräßel
authors.affiliation: Department of Radiology, Stanford University, Lucas Center for Imaging, Stanford, CA 94305, USA.
authors.forename: Maged
authors.initials: M
authors.lastname: Goubran
authors.affiliation: Institute of Anatomy, University of Rostock, Rostock, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Wree
authors.affiliation: Ahmanson-Lovelace Brain Mapping Center, David Geffen School of Medicine UCLA, Los Angeles, USA.
authors.forename: Roger
authors.initials: R
authors.lastname: Woods
authors.affiliation: Institute of Neuroscience and Medicine (INM-1), Research Centre Jülich, Jülich, Germany.|C. and O. Vogt Institute for Brain Research, Heinrich Heine University Düsseldorf, Düsseldorf, Germany.
authors.forename: Katrin
authors.initials: K
authors.lastname: Amunts
authors.affiliation: Institute of Neuroscience and Medicine (INM-1), Research Centre Jülich, Jülich, Germany.|Department of Psychiatry, Psychotherapy and Psychosomatics, RWTH Aachen University, Aachen, Germany.|JARA Jülich-Aachen Research Alliance, Translational Brain Medicine, Jülich, Germany.
authors.forename: Karl
authors.initials: K
authors.lastname: Zilles
mesh_terms: D000328:Adult; D000368:Aged; D000818:Animals; D001345:Autoradiography; D002522:Chlorocebus aethiops; D005260:Female; D006624:Hippocampus / Q000033:anatomy & histology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008859:Microscopy, Polarization / Q000379:methods; D008875:Middle Aged; D019580:Perforant Pathway / Q000033:anatomy & histology
keywords: entorhinal cortex; hippocampus; human circuitry; perforant pathway; polarized light microscopy