Mice turning tiny steering wheels to move shapes on a screen have helped scientists produce the first brain-wide map of decision-making at single-cell resolution in a mammal. In two Nature papers published Sept. 3, an international team of 22 groups, co-led by three Princeton University neuroscience labs, charted the activity of more than 600,000 neurons as mice performed a decision-making task. The resulting dataset offers an unprecedented view of how distributed neural networks work together across the brain to guide behavior.