title: The structure of Pavlovian fear conditioning in the amygdala.
abstract: Do different brains forming a specific memory allocate the same groups of neurons to encode it? One way to test this question is to map neurons encoding the same memory and quantitatively compare their locations across individual brains. In a previous study, we used this strategy to uncover a common topography of neurons in the dorsolateral amygdala (LAd) that expressed a learning-induced and plasticity-related kinase (p42/44 mitogen-activated protein kinase; pMAPK), following auditory Pavlovian fear conditioning. In this series of experiments, we extend our initial findings to ask to what extent this functional topography depends upon intrinsic neuronal structure. We first showed that the majority (87 %) of pMAPK expression in the lateral amygdala was restricted to principal-type neurons. Next, we verified a neuroanatomical reference point for amygdala alignment using in vivo magnetic resonance imaging and in vitro morphometrics. We then determined that the topography of neurons encoding auditory fear conditioning was not exclusively governed by principal neuron cytoarchitecture. These data suggest that functional patterning of neurons undergoing plasticity in the amygdala following Pavlovian fear conditioning is specific to memory formation itself. Further, the spatial allocation of activated neurons in the LAd was specific to cued (auditory), but not contextual, fear conditioning. Spatial analyses conducted at another coronal plane revealed another spatial map unique to fear conditioning, providing additional evidence that the functional topography of fear memory storing cells in the LAd is non-random and stable. Overall, these data provide evidence for a spatial organizing principle governing the functional allocation of fear memory in the amygdala.
authors.affiliation: Department of Psychiatry, School of Medicine, Uniformed Services University (USU), Bethesda, MD, 20814, USA.
authors.forename: Hadley C
authors.initials: HC
authors.lastname: Bergstrom
authors.forename: Craig G
authors.initials: CG
authors.lastname: McDonald
authors.forename: Smita
authors.initials: S
authors.lastname: Dey
authors.forename: Haying
authors.initials: H
authors.lastname: Tang
authors.forename: Reed G
authors.initials: RG
authors.lastname: Selwyn
authors.forename: Luke R
authors.initials: LR
authors.lastname: Johnson
mesh_terms: D000679:Amygdala / Q000166:cytology* / Q000378:metabolism / Q000502:physiology*; D000704:Analysis of Variance; D000818:Animals; D001837:Body Weights and Measures; D001931:Brain Mapping / Q000379:methods; D003214:Conditioning, Classical / Q000502:physiology*; D005239:Fear / Q000502:physiology*; D005455:Fluorescent Antibody Technique; D005786:Gene Expression Regulation / Q000235:genetics*; D007150:Immunohistochemistry; D007395:Interneurons / Q000378:metabolism*; D008279:Magnetic Resonance Imaging; D008297:Male; D008568:Memory / Q000502:physiology*; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D025341:Principal Component Analysis; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D019950:Mitogen-Activated Protein Kinase 1