However, the scans revealed that brain asymmetry -- or which side of the brain is larger -- was opposite in newborns and adults. In adults, the right side of the brain is usually slightly larger than the left side. Gilmore and his collaborators found the left side was slightly larger in the newborns who were included in the study. "What that tells us is that the overall asymmetries in the adult brain occur because of developmental events that happen after birth," Gilmore said. "So unlike the gender differences, the asymmetry differences arise after a baby is born."
For the study, 74 newborns at the University of North Carolina Hospitals were given high-resolution magnetic resonance imaging (MRI) scans in the first few weeks after birth.
In terms of brain volume, the researchers found newborn male brains were 7.8 percent larger than females. In addition, males had 10.2 percent more gray matter and 6.4 percent more white matter than females. No significant difference in brain asymmetry was observed between males and females; the left side of the brain was on average 4.3 percent larger than the right side.
While these findings are intriguing, Gilmore said, they just scratch the surface of an area that has been little studied so far and in which much more research needs to be done.
"This study gives us the first glimpse that there are regional differences in how quickly the brain is growing, and these regional differences are probably related to functional development," he said.
The dramatic growth in gray matter, the part of the brain that contains most of the neurons, or nerve cells, may have implications for autism research, Gilmore said. Children with autism have larger brains and more gray matter than average. The study suggests that in autistic children, something may go awry during gray ma
Source:University of North Carolina School of Medicine