Arc expression identifies the lateral amygdala fear memory trace

• DOI: 10.1038/mp.2015.18
• Publication Date: 2015-03-24T12:48:43Z
• Authors: L A Gouty-Colomer; B Hosseini; I M Marcelo; J Schreiber; D E Slump; S Yamaguchi; A R Houweling; D Jaarsma; Y Elgersma; S A Kushner
• Keywords: Patch-Clamp Techniques; Conditioning, Classical; Action Potentials; Nerve Tissue Proteins; In Vitro Techniques; Choline O-Acetyltransferase; Mice; 03 medical and health sciences; Bacterial Proteins; Memory; Animals; Neurons; EMC ONWAR-01-58-02; 0303 health sciences; Basolateral Nuclear Complex; Glutamate Decarboxylase; Fear; EMC ONWAR-01-94-01; Mice, Inbred C57BL; Cytoskeletal Proteins; Luminescent Proteins; Acoustic Stimulation; Phosphopyruvate Hydratase; Original Article; Central Nervous System Stimulants

Abstract Memories are encoded within sparsely distributed neuronal ensembles. However, the defining cellular properties of neurons within a memory trace remain incompletely understood. Using a fluorescence-based Arc reporter, we were able to visually identify the distinct subset of lateral amygdala (LA) neurons activated during auditory fear conditioning. We found that Arc-expressing neurons have enhanced intrinsic excitability and are preferentially recruited into newly encoded memory traces. Furthermore, synaptic potentiation of thalamic inputs to the LA during fear conditioning is learning-specific, postsynaptically mediated and highly localized to Arc-expressing neurons. Taken together, our findings validate the immediate-early gene Arc as a molecular marker for the LA neuronal ensemble recruited during fear learning. Moreover, these results establish a model of fear memory formation in which intrinsic excitability determines neuronal selection, whereas learning-related encoding is governed by synaptic plasticity.