Converging dopamine pathways onto basolateral amygdala neurons encode exploration decisions

Exploration is a fundamental innate behavior essential for securing survival-necessary resources, but it also increases risks. However, the neural mechanisms encoding exploration decisions remain unknown. Here, we show that social companionship motivates both innate-driven and experience-dependent explorations in mice. Dopaminergic neurons in the ventral tegmental area (VTADA neurons) determine exploration decisions by encoding risky vigilance (via phasic firing) and exploration motivation (via tonic firing). Two subpopulations of VTADA neurons co-innervate the same population of basolateral amygdala neurons via direct and indirect pathways. Tonic firing-biased DA-D2R transmission in the medial prefrontal cortex (indirect pathway) mediates exploratory behaviors, which are reinforced by social interactions, while phasic firing-biased DA-D1R transmission in the direct pathway mediates avoidant behaviors. The dynamic balance between these two…