A fundamental problem in neuroscience is to understand how the brain generates purposeful, coordinated behaviour to achieve internally represented goals. Cognitive control, a hallmark of intelligent behaviour, includes functions such as working memory, decision making and attentional switching. While these phenomena have been traditionally studied in humans and primates, rodents such as mice have sophisticated cognitive abilities as well, and provide an opportunity to develop a detailed circuit-level understanding of cognitive processes. Our lab studies cognition in mice by combining chronic in-vivo two photon calcium imaging of multiple cell classes, targeted optogenetic manipulations, viral vector based functional circuit mapping, and quantitative mouse behavioural assays. We study how projections from prefrontal cortical neurons bias the processing of different sensory and motor areas, through interactions between local network dynamics and long-range inputs.