Organization of Valence-Encoding and Projection-Defined Neurons in the Basolateral Amygdala

TLDR

The basolateral amygdala mediates associative learning for fear and reward, with distinct projection pathways influencing motivated behavior, yet the anatomical arrangement of valence‑encoding neuron subsets remains controversial. The study aims to elucidate the functional and topographical organization of valence‑encoding circuits in the BLA to uncover principles of emotional processing. The authors mapped over 1,000 BLA neurons recorded during a Pavlovian discrimination task, identified projection‑defined neurons using retrograde tracers and CLARITY, and assessed the local influence of each projection within the BLA.

Abstract

The basolateral amygdala (BLA) mediates associative learning for both fear and reward. Accumulating evidence supports the notion that different BLA projections distinctly alter motivated behavior, including projections to the nucleus accumbens (NAc), medial aspect of the central amygdala (CeM), and ventral hippocampus (vHPC). Although there is consensus regarding the existence of distinct subsets of BLA neurons encoding positive or negative valence, controversy remains regarding the anatomical arrangement of these populations. First, we map the location of more than 1,000 neurons distributed across the BLA and recorded during a Pavlovian discrimination task. Next, we determine the location of projection-defined neurons labeled with retrograde tracers and use CLARITY to reveal the axonal path in 3-dimensional space. Finally, we examine the local influence of each projection-defined populations within the BLA. Understanding the functional and topographical organization of circuits underlying valence assignment could reveal fundamental principles about emotional processing.