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Good parenting is essential to the survival of species across the animal kingdom. However, parenting is often linked exclusively to maternal care. Years of insightful scientific work have explored the maternal brain, identifying exactly what molecules give rise to maternal behavior. The research landscape investigating the neuroscience behind paternal care is comparatively barren.
show that both maternal and paternal care crucially shape a child’s development. Why, then, do most studies only look at the neural mechanisms of maternal care? The scientific techniques used address such questions are highly invasive and cannot be used in humans. Neuroscientists thus conventionally turn to non-human mammals. However, very few non-human mammals demonstrate paternal behavior.
recently published in the journal Cell circumvents this issue. The researchers studied both mouse and rat sires — male rodents that have fathered offspring. Mouse sires naturally demonstrate paternal behavior, whereas rat sires do not. To find the difference between the paternal mouse brain and the non-paternal rat brain, they looked at a brain region called the hypothalamus because it has been identified as a key region in maternal parenting behavior.
The hypothalamus receives many inputs, including from neuroendocrine dopamine neurons. As their name suggests, these neurons release dopamine. The researchers measured the amount of dopamine released onto the hypothalamus in mouse and rat sires and found a key difference: the levels of dopamine were higher in rat sires than in mouse sires.
The researchers then tested the hypothesis that higher dopamine levels released onto the hypothalamus lead to reduced paternal behavior. Using optogenetics — a technique that uses light to activate neurons — they manipulated the dopaminergic neurons of the paternal mouse sires to release more dopamine. As predicted, the mouse sires showed impaired paternal behavior.
This addresses an important gap in the scientific literature on parenting. We now know that the rodent brain has built-in mechanisms to regulate paternal behavior. It would be interesting to explore the same effect in human fathers, when scientific techniques advance to be less invasive.