A DOMINANT male mouse won鈥檛 just turn a female on. He鈥檒l make her brain grow. Just a whiff of his odour is enough to make the female鈥檚 brain sprout new neurons, and this growth drives her to want to mate with him.
Samuel Weiss at the University of Calgary in Alberta, Canada, and his colleagues exposed 8 to 10-week-old female mice to soiled bedding from males of the same age. Two weeks later they found that the brains of females exposed to dominant male pheromones had grown significantly more new neurons in two key regions of the brain than those exposed to subordinate pheromones and control odours. What鈥檚 more, these females would then pick the dominant male over the subordinate. Females that had not grown new brain cells did not.
The researchers think the new neurons encode trace memories of dominant males (, DOI: 10.1038/nn1928). Both the olfactory bulb, which processes smell, and the hippocampus, which is involved in memory, have been hailed as main sites for neurogenesis across many species. 鈥淏ut nobody鈥檚 ever linked the two,鈥� says Weiss.
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