A major challenge that makes learning difficult is that the world is complex and high dimensional: there are often multiple possible stimuli or actions to attribute to any outcome, and a gap in time between an event and its consequences. Ilana Witten’s team brings new perspectives and technologies to understand how the brain overcomes these types of challenges, using rodents as the model system. Witten’s lab is also very interested in the ramifications of learning in a complex and high dimensional environment on the emergence of individual differences, including the origin of stress-related maladaptive states.