Adaptive behavior in a dynamically changing environment requires learning the value of actions, and updating these values in response to changes in the environment. Several studies have investigated the role of the striatum, and its key neuromodulators, dopamine (DA) and acetylcholine (Ach), in this process. However, these studies usually investigated these neuromodulatory signals in animals which had undergone extensive pre-training, and were thus experts at flexibly adapting to new action values. In addition, most of these studies did not explore the dynamics of these signals simultaneously, in an individual animal. Thus, it remains unknown how striatal DA and Ach jointly shape learning and updating of action values from naive to expert behavior. To address these questions, we imaged DA and Ach release simultaneously in the dorsal striatum of naive head-fixed mice as they learned to perform a two alternative choice task that featured blocks of trials with different action values. Mice learned to choose the action with the higher value and did so faster as they gained more experience in the task. We observed a diverse range of learning curves, from convex to concave, within and across mice. Both striatal DA and Ach signals showed responses to reward delivery, and these responses decreased as learning progressed. We are currently investigating reinforcement learning models that can capture the variability in learning curves and relate this variability to striatal DA and Ach signals. Together, these experiments will provide novel insights into how stratal neuromodulatory signals jointly shape adaptive behavior.