A team led by Pilyoung Kim at the Universities of Denver and Yale twice scanned the brains of 16 new fathers (average age 36; 7 were first-time dads). The first scan took place between 2 and 4 weeks after their babies were born; the second scan 12 to 16 weeks later. Previous research has shown functional changes in the brains of fathers, in the way that they show heightened neural activity in response to the sight of their own infants. However, this is the first time that researchers have documented structural changes in the brains of human fathers.
Comparing the later scan with the first scan, Kim’s team found increased grey matter volume in several regions of the fathers’ brains. This included areas previously identified as showing growth in new mothers, including the striatum (involved in reward processing, among other functions), hypothalamus (hormonal control), amygdala and anterior cingulate cortex (ACC; involved in emotional processing), and the lateral pre-frontal cortex (PFC; involved in memory and decision making). The PFC is one of the areas that has been associated with heightened activity when fathers view their own infants. Prior monkey researchhas also shown an increase in branching between neurons in the PFC of fathers.