Fetal brain scans reveal "blueprint" of the adult brain
Our functional connectome -- the brain's "fingerprint" -- may take shape in the womb.
The blueprint of the adult brain may be mapped out far earlier than we thought. In fact, some 60 percent of the circuits that make up the adult brain may take shape before we are even born, according to a new study.
The groundwork for a lifetime of brain development is laid in gestation. Regions of the fetal brain start to wire together, forming early signatures of what scientists call the “functional connectome,” according to a paper published in The Journal of Neuroscience.
As a child grows, the brain changes: certain connections are pruned as they develop, and during adolescence, regions of the brain related to planning and and self-control fight to come online.
The functional connectome is a series of well-traveled highways in the brain that are fully operational when we’re adults. The new data suggest that the dirt paths underlying those highways are present in fetuses as early as the second trimester.
“We have this connectional blueprint,” Moriah Thomason, lead author and professor at New York University’s School of Medicine tells Inverse. “Across the second and third trimester it begins to start advancing into something you’d recognize as an adult-like structure.”
The results are based off fMRI images of 105 fetal brains taken while they were developing in the womb. Imaging fetal brains as they’re developing is a new and delicate process. “All that we’ve understood about the fetus all these years comes from snapshots,” Thomason says. “The fetus was quite a black box, and this is the first technology we’ve had to measure and map function.”
Fetuses in the womb tend to move around, so the team had to wait for periods of stillness before they could collect their scans. But once they had the scans in hand, the scientists then analyzed the compiled scans for patterns of brain activity. When they compared those activity maps to those seen in adult brains, they found that there was 61 percent overlap between the two.
Lucina Uddin, Ph.D., a neuroscientist at the the University of Miami says that these results show just how early the adult brain’s networks begin to emerge.
“These results suggest that the basic layout of the functional connectome in the human brain is established earlier than previously reported,” she tells Inverse.
What does this “fingerprint” tell us?
The findings suggest that the blueprint for the adult connectome is strikingly complete early in life. But it’s still just a blueprint. As a child grows up, brain connections will strengthen and diversify. But like any building project, that means things don’t always go as planned.
Exposure to environmental factors, like alcohol, stress, air pollution or other chemicals, during pregnancy can affect child development in lasting ways.
Now that scientists have an early map of the brain in development they may be able to spot what and how different factors can push brain development off track, what the long-term consequences are, and perhaps find ways to protect against them.
“We would want to understand consequences: if you disrupt that processes does the child have a language disorder or autism? However, we can’t do those studies until we understand normative processes,” says Thomason.
Thanks to the brain scans of 105 fetuses, scientists are finally starting to get a clearer picture.
Large-scale functional connectome formation and re-organization is apparent in the second trimester of pregnancy, making it a crucial and vulnerable time window in connectome development. Here we identified which architectural principles of functional connectome organization are initiated prior to birth, and contrast those with topological characteristics observed in the mature adult brain. A sample of 105 pregnant women participated in human fetal resting-state fMRI studies (fetal gestational age between 20 and 40 weeks). Connectome analysis was used to analyze weighted network characteristics of fetal macroscale brain wiring. We identified efficient network attributes, common functional modules and high overlap between the fetal and adult brain network. Our results indicate that key features of the functional connectome are present in the second and third trimesters of pregnancy. Understanding the organizational principles of fetal connectome organization may bring opportunities to develop markers for early detection of alterations of brain function.