Preterm babies (by definition any infant born before completing 37 gestational weeks) — particularly those born significantly earlier — are at increased risk for sensory, motor, and cognitive challenges. They also experience a higher incidence of developmental impairments. Scientists know that every week a baby spends in the womb is critical for healthy development, but the specific changes that impact the developing brain of preterm babies are not yet fully understood. Researchers at BC Children’s Hospital Research Institute (BCCHR) are investigating how the brain functions at an early gestational age so they can identify potential therapies.
“As a result of two complementary studies, we found that the brain networks of preterm babies are slower to enter what we call a critical state, as it is not until term-equivalent age that their networks become efficient,” says Dr. Alexander Weber, investigator at BCCHR and assistant professor in the Department of Pediatrics at the University of British Columbia (UBC). During birth, infants are exposed to a different external environment compared to the womb, which has a huge impact on babies, particularly preterms. But being born preterm is not the only important factor impacting the developing brain. Dr. Weber’s research found new evidence that the younger a baby is born, the slower their brain development will be.
In one study, published in the PLOS Complex Systems Journals, Dr. Weber’s team analyzed data from the Hospital for Sick Children, where preterm babies were scanned shortly after they were born and, again, when the babies reached term-equivalent age. In another study, published in the Cerebral Cortex Journal, publicly available data from the Developing Human Connectome Project was investigated, which included scans from both term and preterm infants.
The data from both studies allowed us to compare scans from preterm babies — scanned shortly after birth and again at term-equivalent age — with term babies, which was key to help us measure the development of brain activity.
– Dr. Alexander Weber
The brain scans used in both studies were functional magnetic resonance imaging (fMRI), which measures blood-oxygen-level-dependent (BOLD) signals. The BOLD signal is a way of representing blood flow and oxygenation in different areas of the brain, acting as a surrogate for where brain activity is occurring. The advantage of this method is the possibility to assess functional brain activity and networks in a non-invasive way. Networks are different parts of the brain that work in sync or collaboratively, but with distinct functions, such as the auditory and visual networks.
“The data from both studies allowed us to compare scans from preterm babies — scanned shortly after birth and again at term-equivalent age — with term babies, which was key to help us measure the development of brain activity,” says Dr. Weber. “When doing fMRI studies, it’s common to use a spatial method, which consists of looking at which areas of the brain are communicating and acting as networks, and then comparing how those networks are different between groups; for example, preterm and term. But we’re more interested in a temporal method, which helps measure complex systems, including the brain.”
In neuroscience, the critical brain hypothesis theory claims that the brain operates at its best at a point between disorder and order — the critical state. “In our studies, the brain networks in preterms were still in the disordered phase, and started moving towards a more ordered, and still complex phase by term age,” says Dr. Weber. “That means the brains of preterm babies were not yet in a critical state. Once they entered the critical state, we believe their brains were becoming more optimal and efficient.”
Dr. Weber’s team will continue to explore the neuroscience of brain development and expand on these findings. The goal is to find out what structures in the brain are causing the differences in brain development of preterm and term babies. For example, very preterm babies (infants born before 32 weeks) usually have white matter injuries or other events that reduce the amount of oxygen in the brain. Understanding how these injuries lead to a slower transition into a critical state can help inform therapies.
While preterm babies are at higher risk of neurodevelopmental impairments, many thrive. Our research team aims to understand the changes in the brain that support children to flourish, even when born early.
– Dr. Steven Miller
“While preterm babies are at higher risk of neurodevelopmental impairments, many thrive. Our research team aims to understand the changes in the brain that support children to flourish, even when born early,” Dr. Steven Miller, investigator at BCCHR, head of the Department of Pediatrics at UBC, and Chief of Pediatric Medicine at BC Children’s Hospital & Sunny Hill Health Centre. Dr. Miller is working with Dr. Weber in this research.
