THE NAKED SCIENTISTS - Mice are genuinely fearful of cats; and when they encounter the aroma of a feline, they freeze and then scarper. This happens thanks to an accessory smell system called the vomeronasal organ, or VNO. One of its roles is to detect pheromones, and its wiring into the limbic system enables it to coordinate mating behaviours. But it can also detect predator smells, including cats, and projections to the hypothalamus initiate defensive responses. Interestingly, the extent of these responses is not binary; they’re proportional to the intensity of the stimulus. Speaking with Chris Smith, Sachiko Haga-Yamanaka, from the University of California, Riverside, has used cat tears, which contain odourants that the mouse VNO is sensitive to, to unpick the neurological pathways responsible…