title: An organization of visual and auditory fear conditioning in the lateral amygdala.
abstract: Pavlovian fear conditioning is an evolutionary conserved and extensively studied form of associative learning and memory. In mammals, the lateral amygdala (LA) is an essential locus for Pavlovian fear learning and memory. Despite significant progress unraveling the cellular mechanisms responsible for fear conditioning, very little is known about the anatomical organization of neurons encoding fear conditioning in the LA. One key question is how fear conditioning to different sensory stimuli is organized in LA neuronal ensembles. Here we show that Pavlovian fear conditioning, formed through either the auditory or visual sensory modality, activates a similar density of LA neurons expressing a learning-induced phosphorylated extracellular signal-regulated kinase (p-ERK1/2). While the size of the neuron population specific to either memory was similar, the anatomical distribution differed. Several discrete sites in the LA contained a small but significant number of p-ERK1/2-expressing neurons specific to either sensory modality. The sites were anatomically localized to different levels of the longitudinal plane and were independent of both memory strength and the relative size of the activated neuronal population, suggesting some portion of the memory trace for auditory and visually cued fear conditioning is allocated differently in the LA. Presenting the visual stimulus by itself did not activate the same p-ERK1/2 neuron density or pattern, confirming the novelty of light alone cannot account for the specific pattern of activated neurons after visual fear conditioning. Together, these findings reveal an anatomical distribution of visual and auditory fear conditioning at the level of neuronal ensembles in the LA.
authors: Department of Psychiatry, Uniformed Services University (USU), School of Medicine, Bethesda, MD 20814, United States; Center for the Study of Traumatic Stress (CSTS), Bethesda, MD 20814, United States.
authors: Hadley C
authors: HC
authors: Bergstrom
authors: Department of Psychiatry, Uniformed Services University (USU), School of Medicine, Bethesda, MD 20814, United States; Center for the Study of Traumatic Stress (CSTS), Bethesda, MD 20814, United States; Program in Neuroscience, Uniformed Services University (USU), School of Medicine, Bethesda, MD 20814, United States; Translational Research Institute (TRI), Institute for Health and Biomedical Innovation (IHBI), Department of Psychology and Counselling, Queensland University of Technology (QUT), Brisbane, QLD, Australia. Electronic address: lukejohnsonphd@gmail.com.
authors: Luke R
authors: LR
authors: Johnson
mesh_terms: D000161:Acoustic Stimulation; D000679:Amygdala / Q000378:metabolism / Q000502:physiology*; D000818:Animals; D002452:Cell Count; D003214:Conditioning, Classical / Q000502:physiology*; D003463:Cues; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005239:Fear / Q000502:physiology*; D008297:Male; D008568:Memory / Q000502:physiology; D009474:Neurons / Q000378:metabolism / Q000502:physiology*; D010766:Phosphorylation; D010775:Photic Stimulation; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D048049:Extracellular Signal-Regulated MAP Kinases
keywords: Basolateral amygdala; Brain mapping; Defensive conditioning; Memory consolidation; Memory strength; Microcircuit; Neuronal ensemble; Threat conditioning