Modeling the lateral amygdala during fear acquisition [abstract]

Abstract

The lateral nucleus of the amygdala (LA) has been shown to play an important role in the acquisition of fear. In rat experiments performed by our collaborator and others, a conditioned stimulus (CS), such as tone, was paired with an unconditioned stimulus (US), such as shock, during fear learning. After the fear conditioning, when the tone was given without the shock, rats continued to freeze and indicate fear. For better understanding of this fear acquisition, we studied the neuroplasticity mechanisms that underlie learning and created a model that corresponds to the experiments. Studies published on the neuroplasticity mechanisms of fear conditioning revealed that NMDA receptors (NMDARs), AMPA receptors (AMPARs), and L-type voltage-gated calcium channels (VGCCs) are particularly involved in learning fear by increasing channel conductance and allowing more calcium to flow into the postsynaptic cell by the activation of Ca2+/calmodulin-dependent protein kinase II (CaMKII). We incorporated these findings in a computational model, which consists of two pyramidal neurons and an interneuron, and implemented learning rules to modulate the synaptic weights. Model predictions exhibit trends similar to those observed in experiments by our collaborator. As the model becomes more accurate, it will allow us to predict the consequence of changes in the channels, the synaptic weights and other parts of the cell that experiments have not yet revealed.