Newly-born neurons in the hippocampus and olfactory bulb ― areas of the brain implicated in memory and olfaction, respectively ― are crucial for helping male mice recognize their own offspring, reports a study published online this week in Nature Neuroscience. The results suggest that a father's recognition of their adult offspring is based on the experiences of fatherhood, and the production of new neurons and neural hormones are crucial for this process.
Fathers' recognition of their juvenile and adult offspring is known to occur in non-human primates, humans, and some species of wild rodents. Samuel Weiss and Gloria Mak discovered that laboratory strains of male mice will also recognize their own pups as adults if the fathers are given the chance to interact and care for their genetic offspring. This paternal recognition of genetic offspring was accompanied by higher neurogenesis ― creation of new neurons ― in the paternal olfactory bulb and hippocampus, where new neurons are continually generated in adulthood.
The researchers also found that prolactin, a hormone produced by the pituitary gland, is required for the paternal offspring recognition. Male mice lacking this hormone did not show enhanced adult neurogenesis upon pup interaction and failed to recognize their progeny.
Enhancing neurogenesis with a different hormone made up for the lack of prolactin, resulting in restored offspring recognition in male parents. It remains untested whether a similar mechanism is required in human offspring recognition or whether this could affect subsequent father-child behaviors.