Ensemble coding in amygdala circuits for associative learning.

Associative fear learning in the basolateral amygdala (BLA) is crucial for an animal's survival upon environmental threats. BLA neurons are defined on the basis of their projection target, genetic markers, and associated function. BLA principal neuron responses to threat signaling stimuli are potentiated upon associative fear learning, which is tightly controlled by defined interneuron subpopulations. In addition, BLA population activity correlates with behavioral states and threat or safety signals. BLA neuronal ensembles activated by different behavioral signals can be identified using immediate early gene markers. The next challenge will be to determine the activity patterns and coding properties of defined BLA ensembles in relation to the whole neuronal population.