•Tasks are needed to engage brain networks relevant to specific cognitive functions.•Recent approaches enable the control of activity in selected neurons during behavior.•Advanced techniques make it possible to simultaneously record thousands of neurons.•Novel analysis methods have improved assessment of neural and behavioral data.•Combining these approaches in mice will reveal new insight into cognitive functions. Understanding how cognitive functions arise from computations occurring in the brain requires the ability to measure and perturb neural activity while the relevant circuits are engaged for specific cognitive processes. Rapid technical advances have led to the development of new approaches to transiently activate and suppress neuronal activity as well as to record simultaneously from hundreds to thousands of neurons across multiple brain regions during behavior. To realize the full potential of these approaches for understanding cognition, however, it is critical that behavioral conditions and stimuli are effectively designed to engage the relevant brain networks. Here, we highlight recent innovations that enable this combined approach. In particular, we focus on how to design behavioral experiments that leverage the ever-growing arsenal of technologies for controlling and measuring neural activity in order to understand cognitive functions.