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.,
Molecular Psychiatry
Department of Neuroscience

Gouty-Colomer, L.A, Hosseini, B, Marcelo, I.M, Schreiber, J, Slump, D.E, Yamaguchi, S, … Kushner, S.A. (2016). Arc expression identifies the lateral amygdala fear memory trace. Molecular Psychiatry, 21(3), 364–375. doi:10.1038/mp.2015.18