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Neurobiol Learn Mem. 2016 Jan;127:64-71. doi: 10.1016/j.nlm.2015.11.010. Epub 2015 Nov 28.

A dendritic organization of lateral amygdala neurons in fear susceptible and resistant mice.

Author information

1
Program in Neuroscience and Department of Psychiatry, Uniformed Services University (USU), School of Medicine, Bethesda, MD 20814, USA; Department of Biosystems Engineering, Federal University of São João del Rei (UFSJ), São João del Rei, MG 36307-352, Brazil.
2
Program in Neuroscience and Department of Psychiatry, Uniformed Services University (USU), School of Medicine, Bethesda, MD 20814, USA; Department of Psychology and Neuroscience and Behavior Program, Vassar College, Poughkeepsie, NY 12603, USA.
3
Program in Neuroscience and Department of Psychiatry, Uniformed Services University (USU), School of Medicine, Bethesda, MD 20814, USA.
4
Department of Psychology and Program in Neuroscience, Middlebury College, Middlebury, VT 05753, USA.
5
Department of Psychology, Pontifical Catholic University of Rio de Janeiro (PUC-Rio), Rio de Janeiro, RJ 22451-900, Brazil.
6
Program in Neuroscience and Department of Psychiatry, Uniformed Services University (USU), School of Medicine, Bethesda, MD 20814, USA; Center for the Study of Traumatic Stress (CSTS), Bethesda, MD 20814, USA.
7
Department of Human Genetics, University of Chicago, IL 60637, USA; Department of Psychiatry and Behavioral Neuroscience, University of Chicago, IL 60637, USA.
8
Program in Neuroscience and Department of Psychiatry, Uniformed Services University (USU), School of Medicine, Bethesda, MD 20814, USA; Center for the Study of Traumatic Stress (CSTS), Bethesda, MD 20814, USA; School of Psychology and Counseling, Queensland University of Technology (QUT), Brisbane, QLD 4059, Australia; Translational Research Institute (TRI), Brisbane, QLD 4102, Australia. Electronic address: LukeJohnsonPhD@gmail.com.

Abstract

Subtle differences in neuronal microanatomy may be coded in individuals with genetic susceptibility for neuropsychiatric disorders. Genetic susceptibility is a significant risk factor in the development of anxiety disorders, including post-traumatic stress disorder (PTSD). Pavlovian fear conditioning has been proposed to model key aspects of PTSD. According to this theory, PTSD begins with the formation of a traumatic memory which connects relevant environmental stimuli to significant threats to life. The lateral amygdala (LA) is considered to be a key network hub for the establishment of Pavlovian fear conditioning. Substantial research has also linked the LA to PTSD. Here we used a genetic mouse model of fear susceptibility (F-S) and resistance (F-R) to investigate the dendritic and spine structure of principal neurons located in the LA. F-S and F-R lines were bi-directionally selected based on divergent levels of contextual and cued conditioned freezing in response to fear-evoking footshocks. We examined LA principal neuron dendritic and spine morphology in the offspring of experimentally naive F-S and F-R mice. We found differences in the spatial distribution of dendritic branch points across the length of the dendrite tree, with a significant increase in branch points at more distal locations in the F-S compared with F-R line. These results suggest a genetic predisposition toward differences in fear memory strength associated with a dendritic branch point organization of principal neurons in the LA. These micro-anatomical differences in neuron structure in a genetic mouse model of fear susceptibility and resistance provide important insights into the cellular mechanisms of pathophysiology underlying genetic predispositions to anxiety and PTSD.

KEYWORDS:

Amygdala; Associative learning; Individual differences; Microanatomy; PTSD; Spines

PMID:
26642919
DOI:
10.1016/j.nlm.2015.11.010
[Indexed for MEDLINE]

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