In the brains of mothers the infanticide switch

Discovered the brain switch that pushes mothers to kill their young: identified in female mice, it could play a similar role in women, opening a new way to prevent infanticide. The result is published in Nature by NYU Grossman School of Medicine in the United States.

The brain switch that triggers infanticide is located in a region of the midbrain linked to emotion control and known as the 'main nucleus of the bed nucleus of the stria terminalis' (BNSTpr). The inhibition of this region in female mice prevents almost 100% of infanticides; Its activation, on the other hand, causes the females to attack their own and others' puppies within just a second. Attacks on other adult specimens have rarely been recorded, suggesting that the structure specifically controls aggression towards the young.

The study shows that the BNSTpr region performs the opposite action compared to another brain region (called the 'medial preoptic area', MPOA) which promotes caring behavior towards offspring. In female mice that have not yet given birth, the BNSTpr region is more active, which inhibits MPOA: this often causes them to kill the puppies of other females, probably to ensure more resources for their future litter. After giving birth, the situation is reversed: MPOA's activity increases, curbing aggression towards puppies and therefore avoiding their killing.

"Because these two communicating regions in the middle of the brain can be found in both rodents and humans," says neuroscientist Dayu Lin, who coordinated the study, "our findings suggest a possible target for understanding, and perhaps even treating, mothers who abuse their children. These cells may normally remain dormant, but stress, postpartum depression and other known triggers for child abuse can prompt them to become more active."