Dietary restriction – the reduction of a specific nutrient or total dietary intake without triggering malnutrition—increases longevity and improves learning, but are these processes regulated separately? A new study publishing on August 1 in the open access journal PLOS Biology by Mihir Vohra, Kaveh Ashrafi and colleagues at the University of California at San Francisco, indicates that the answer is “yes.” The team shows that depletion of a single amino acid metabolite improves learning in an experimental animal, but has no effect on lifespan.