The distinct subpopulations in parafascicular thalamic nucleus encoding innate emotional valence

A fundamental question in neuroscience is how animals adapt their behaviors to pursue rewards and avoid punishments. Our findings demonstrate that exposure to appetitive and aversive valence stimuli enhances c-Fos expression and calcium signaling in the parafascicular thalamic nucleus (PF). We identified two distinct populations of PF neurons that respectively encode appetitive or aversive emotional valence. Furthermore, we show that the subpopulations within PF projecting to ventral tegmental area (VTA) or periaqueductal gray (PAG) are anatomically segregated, and PF-VTA and PF-PAG circuits mediate appetitive and aversive behaviors, respectively. Altered neuronal activity of these PF populations following stress subserve related depression-like phenotypes and altered valence responses. These findings enhance our understanding of the role of the PF and its neural circuits in emotional processing and their dysregulation in depressive disorders.