A Circult Mechanism for Differentiating Positive and Negative Associations

The ability to differentiate stimuli predicting positive or negative outcomes is critical for survival, and perturbations of emotional processing underlie many psychiatric disease states. Different neuronal populations of the basolateral amygdala complex (BLA) encode fearful or rewarding associations, but the molecular identity of these functionally distinct populations of BLA neurons remained unknown. Here, we show that BLA neurons projecting to the nucleus accumbens (NAc-projectors) or the centromedial amygdala (CeM-projectors) underwent opposing synaptic changes following fear or reward conditioning. The photostimulation of NAc projectors supported positive reinforcement while photostimulation of CeM projectors mediated negative reinforcement. In search of defining molecular characteristics of these functionally-distinct BLA neuronal populations, we compared gene expression profiles of NAc- and CeM-projectors. For comparison of gene expression profiles of NAc- and CeM-projectors, we conducted two independent RNA sequencing experiments. In experiment-1, a total of n=9 samples (n=4 NAc- and n=5 CeM-projectors) are analyzed. In experiment-2, a total of n=8 samples (n=4 NAc- and n=4 CeM-projectors) are analyzed.