Despite decades of research on the properties of ventral tegmental area (VTA) dopamine neurons, the precise information encoded by these cells in reward learning and motivated behavior remains uncertain. In this talk, I will describe recent work investigating two distinct modalities of the midbrain dopamine system at different levels of investigation. First, I will present work leveraging an approach that combines Neuropixels recordings and optogenetics to examine dopamine neurons at the single-cell level. In conjunction with computational modeling, we explored the neural dynamics of dopamine subpopulations across different VTA subregions in mice performing a reward-seeking task. Second, I will discuss a neural mechanism that explains why a chronic high-fat diet paradoxically diminishes the desire for high-fat, sugary foods, even when these foods are easily accessible. We found that this reduction in desire is attributed to decreased neurotensin signaling from nucleus accumbens inputs to dopamine neurons in the lateral VTA. We propose that restoring this desire, either through dietary modifications or by enhancing neurotensin expression and release, can drive changes in eating behavior and promote weight loss. Together, our experiments are geared towards developing comprehensive frameworks for understanding dopamine’s diverse roles in behavior.