Danger could make you smell new odors. In testing volunteers, scientists at Northwestern University used odor molecules that have the same chemical formula but are structured to be mirror opposites, like left and right hands. Such molecules ordinarily smell identical to people. But after getting zapped with mild electrical shocks when exposed to one molecule but not when sniffing the other, volunteers rapidly learned to easily tell them apart. Functional MRI scans suggest that strong emotions could make the ancient smell centers of the brain quickly learn subtle differences between odors. The hypersensitivity seen in patients with some anxiety disorders could arise from a faulty ability to distinguish between true signals of danger and similar but less vital stimuli, the Northwestern team speculates, adding that its research could help develop new therapies. The electrifying findings appear in the March 28 Science.