The smell of their pups alters the neural responses of lactating female mice, making the mothers more sensitive to pup sounds.

Adi Mizrahi and his colleagues at the Hebrew University of Jerusalem in Israel recorded the activity of single neurons in the primary auditory cortex of female mice. They found a more variable neuronal firing rate in lactating mothers exposed to pup odours than in lactating animals exposed to nesting materials or in virgin females. In an experimental test of maternal behaviour, both mothers and virgins with experience of pups responded to the cries of pups that had strayed from the nest and retrieved them, whereas naive virgins did not. Furthermore, the auditory neurons of females that had interacted with pups were more sensitive to certain pup sounds than those of naive females.

Neuron 72, 357–369 (2011)