A computational model of the fear circuit was developed to study regulation of fear by amygdala intercalated (ITC) neurons within the amygdala. A new biophysical model of an ITC neuron was developed first to capture its bistable behavior caused by an unusual slowly deinactivating current. An existing lateral amygdala network model was then extended into an overall fear circuit by adding ITC neurons, together with additional amygdaloid structures. Using a biophysical Hebbian learning rule for plastic synapses, the model successfully simulated the amygdala responses during acquisition, extinction, and recall of extinction in auditory fear conditioning. Results showed that fear could be regulated by the bistability of ITC neurons. The model also suggested additional sites for the storage fear and extinction memories.
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