Conditioned appetitive and aversive responses (CRs) are thought to result from the activation of specific subsets of valence-coding basolateral amygdala (BLA) neurons. Under this model, the responses of BLA cells to conditioned stimuli (CSs) and the activity that drives CRs are closely related. We tested the strength of this correlation using a task where rats could emit different CRs in response to the same CSs. At odds with this model, the CS responses and CR-related activity of individual BLA cells were separable. Moreover, while the incidence of valence-coding cells did not exceed chance, at the population level there was similarity between valence coding for CSs and CRs. In fact, both lateral and basolateral neurons concurrently encoded multiple task features and behaviors. Thus, conditioned emotional behaviors may not depend on the recruitment of single cells that explicitly encode individual task variables but from multiplexed representations distributed across the BLA. Kyriazi et al. show that most BLA neurons concurrently encode multiple task features, including the sensory properties of CSs and the behaviors they elicit. This leads to multiple task dimensions being represented at the population level.
Kyriazi, P., Headley, D. B., & Pare, D. (2018). Multi-dimensional Coding by Basolateral Amygdala Neurons. Neuron, 99(6), 1315-1328.e5. https://doi.org/10.1016/j.neuron.2018.07.036