ORIGINAL RESEARCH published: 14 March 2017 doi: 10.3389/fnana.2017.00016 Elucidation of White Matter Tracts of the Human Amygdala by Detailed Comparison between High-Resolution Postmortem Magnetic Resonance Imaging and Histology Susumu Mori 1 *, Yusuke Kageyama 2 , Zhipeng Hou 1 , Manisha Aggarwal 1 , Jaymin Patel 1 , Timothy Brown 3 , Michael I. Miller 3,4,5 , Dan Wu 1 and Juan C. Troncoso 2 1 Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, USA, 2 Department of Pathology, Division of Neuropathology, Johns Hopkins University School of Medicine, Baltimore, MD, USA, 3 Center for Imaging Science, Johns Hopkins University, Baltimore, MD, USA, 4 Institute for Computational Medicine, Johns Hopkins University, Baltimore, MD, USA, 5 Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, USA Edited by: Ricardo Insausti, University of Castilla–La Mancha, Spain Reviewed by: Zoltan Rusznak, Australian Catholic University, Australia Frasncisco E. Olucha-Bordonau, Jaume I University, Spain *Correspondence: Susumu Mori smori1@jhmi.edu Received: 09 October 2016 Accepted: 20 February 2017 Published: 14 March 2017 Citation: Mori S, Kageyama Y, Hou Z, Aggarwal M, Patel J, Brown T, Miller MI, Wu D and Troncoso JC (2017) Elucidation of White Matter Tracts of the Human Amygdala by Detailed Comparison between High-Resolution Postmortem Magnetic Resonance Imaging and Histology. Front. Neuroanat. 11:16. doi: 10.3389/fnana.2017.00016 The amygdala has attracted considerable research interest because of its potential involvement in various neuropsychiatric disorders. Recently, attempts have been made using magnetic resonance imaging (MRI) to evaluate the integrity of the axonal connections to and from the amygdala under pathological conditions. Although amygdalar pathways have been studied extensively in animal models, anatomical references for the human brain are limited to histology-based resources from a small number of slice locations, orientations and annotations. In the present study, we performed high-resolution (250 μm) MRI of postmortem human brains followed by serial histology sectioning. The histology data were used to identify amygdalar pathways, and the anatomical delineation of the assigned structures was extended into 3D using the MRI data. We were able to define the detailed anatomy of the stria terminalis and amygdalofugal pathway, as well as the anatomy of the nearby basal forebrain areas, including the substantia innominata. The present results will help us understand in detail the white matter structures associated with the amygdala, and will serve as an anatomical reference for the design of in vivo MRI studies and interpretation of their data. Keywords: white matter anatomy, amygdala, MRI, diffusion tensor imaging, microimaging, histology, stria terminalis, amygdalofugal pathway INTRODUCTION It is widely accepted that the amygdala is involved in various emotional responses (reviewed by Amaral, 2003; Phelps and LeDoux, 2005), in which white matter connectivity plays an essential role. Amygdalar connectivity has been studied extensively using animal models, which have shown that the stria terminalis and amygdalofugal pathways serve two major connections of the amygdala. The stria terminalis is an efferent pathway that connects the amygdala to the septal area of the basal forebrain and hypothalamus. It is a poorly myelinated tract, 2–4 mm in diameter, which has only Frontiers in Neuroanatomy | www.frontiersin.org 1 March 2017 | Volume 11 | Article 16