Learning requires trying new things, evaluating the outcomes, and modifying future performance. We are interested in how these processes are implemented in the brain. To distinguish general principles from behavior-, effector-, and species-specific solutions to motor control problems, we study vocal communication and social interaction in both songbirds and parrots, two species with distinct behaviors, learning capacities and neural circuitry. We also compare neural mechanisms by which mice aim their limbs and tongues. We combine electrophysiology, optogenetics, and machine learning-guided behavioral analysis. Our guiding philosophy is that comparative approaches in systems neuroscience, though rare, are necessary to discover core functions of cortex, basal ganglia and cerebellum - brain regions that go awry in disorders such as Parkinson's, dystonia, and ADHD.