Fatherhood can result in increased grey matter volume in several regions of the brain, a new study has found.
A team led by researcher Pilyoung Kim at the Universities of Denver and Yale scanned the brains of 16 new fathers twice.
The first scan took place between 2 and 4 weeks after their babies were born and the second scan was taken 12 to 16 weeks later.
This is the first time that researchers have documented structural changes in the brains of human fathers, the study said.
Comparing the later scan with the first scan, Kim's team found increased grey matter volume in several regions of the fathers' brains, according to 'wired.Com'.
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.
The new research also uncovered several brain regions that appeared to shrink in early fatherhood.
The regions displaying reduced grey matter volume included medial pre-frontal cortex, post-central sulcus, precuneus, and inferior parietal cortex, all of which are considered part of the "default mode network".
This group of brain regions tends to become collectively more active as we switch off from the outside world.
Kim and her colleagues speculated that the shrinking of these brain regions could reflect a "shift of resources" away from the default-mode network, in line with fathers' new vigilance for their offspring.
Other regions that showed reduced grey matter included the orbitofrontal cortex (OFC) and the left insula - these regions have previously been implicated in anxiety, and the researchers said that their shrinkage could reflect a diminishing of fathers' anxiety over the first few months of their infants' lives.
