Xiao et al. find that pontine central gray (PCG) contributes to encoding positive and negative valences through the activity of its GABAergic and glutamatergic neurons, respectively, which mediate sensory-induced reward- and aversion-related behaviors. Thus, PCG may serve as a critical hub for the bottom-up processing of sensory valence preceding the limbic system.

Hierarchical processing requires activity propagating between higher and lower-order cortical areas. However, neuroimaging studies have chiefly quantified fluctuations within fixed regions over time rather than propagations over space. We used recent advances in neuroimaging and computer vision to demonstrate that top-down propagations become more prominent during task demands and over…