Cover legend: Electromyograph recordings from the diaphragm muscle as a rat sniffs odors. These recordings were not taken simultaneously, but display the variability in sniffing behavior across different behaviors. Rats adjust their sniff strategies to detect components of mixtures depending on the sorptiveness of the target odor. The rat in the pictures is sniffing perfume. For more information, see the article by Rojas-Líbano and Kay (pages 15577–15589)