Infant brain structure can predict function later in life
February 17, 2017
The human brain undergoes the vast majority of its growth very early in life, and that growth results in the connections that shape how we think and act. Scientists from the UNC School of Medicine’s Early Brain Development Program have tracked how those connections form in the earliest phase of life.
Using advanced MRI imaging, researchers followed the development of infant white matter through the first two years of life. They found that common threads in the structure of white matter can predict cognitive function and are moderately influenced by genetics. The research was published in the Proceedings of the National Academy of Sciences.
Dr. John Gilmore, director of the Early Brain Development Program and senior author of the study performed diffusion tensor imaging (DTI) on a total of 685 children at several periods between their births and second birthdays. DTI scans, like their MRI cousins, use non-damaging magnetic fields and radio waves instead of the high-energy radiation of an X-Ray or CT scan so they are safer for infants and toddlers.
DTI scans track the flow of water in and out of brain cells, and based on how smooth or turbulent that flow is, doctors can map the microscopic structure of the brain’s white matter. Doctors use DTI scans to track brain injuries and study cognitive dysfunctions, but in this case, Gilmore was monitoring how, on a microscopic level, white matter develops in the first two years of life.
The brain’s white matter (pictured below) is made up of the axons of the nerve cells: the long conducting wires that carry signals from one nerve cell to the next. The axons’ branched ends can connect to dozens of other nerve cells, and as the brain becomes more interconnected, senses, thoughts and memories can become more sophisticated. The brain makes 95 percent of these connections by age six, so learning how these connections develop is extremely important in understanding how the brain develops.
Abnormalities in the microscopic structure of white matter has been linked to sensory issues, schizophrenia, autism and other disorders, demonstrating how important white matter is for proper brain function.
The researchers focused on common factors in 12 tracts of white matter throughout the brain, and they searched not only for how those common factors matured over two years, but also how patterns in the white matter at birth influenced the structure and the babies’ cognitive development at ages one and two.
They found that among the 685 infants in the study, everyone’s white matter was pretty much the same at birth, with only minor differences. But as the infants grew, their white matter began to differentiate into more unique patterns.
Further, even though the differences in white matter were very minor at birth, those differences greatly influenced what the white matter looked like later in life, as well as cognitive development at age one and language development at age two.
In addition, the study included 429 twins so Gilmore and the others could also look at how genetics played into white matter development. In the paper, the researchers described the common factors as “moderately heritable,” meaning that while genetics has some influence over what white matter looks like, other factors also have an influence.
What these results show is that there are clear indicators at birth of how the brain will develop, as well as how that development relates to brain function later in life. Therefore, DTI scans could be used to predict brain function, sensory disorders and language ability from a very young age.
This is the first study that examines the microstructure of white matter at such a young age, so for DTI scans to be predictive of how the brain will develop later in life, more studies and more data will be needed. Still, as we learn more about how the brain develops, we can better learn how to keep it healthy.
Daniel Lane covers science, medicine, engineering and the environment in North Carolina.