How Learning Changes the Brain

Mareike Grotheer investigates the Biological Foundations of Cognitive Human Development.
 

Why do some children seem to learn effortlessly, while others need more support? And how do adults manage to acquire new skills over the course of decades? Neuroscientist Mareike Grotheer, who joined the Institute in May 2026 as Head of a Lise Meitner Group, is looking for answers to these questions. Her research addresses the biological foundations of human’s ability to learn, focusing on a neural component that has long been overlooked: changes in the brain’s myelin content.

Myelin is a fatty layer that wraps around nerve fibers in the brain and thereby accelerates the transmission of electrical signals. "You can think of it like the plastic insulation around an electrical wire—without it, the current does not flow correctly," Grotheer explains. For a long time, scientists thought that myelin is relatively stable and changes little once it has been established. However, animal studies have shown that if myelin formation is disrupted, mice lose their ability to learn. Research on the role of myelin in human learning is still in its early stages.

That's where the work of Grotheer and her new research group comes in. Their key tool is quantitative magnetic resonance imaging (qMRI)—a method that measures myelin content across the brain and can track changes over time. The scans take longer than conventional MRI, and the data require complex analyses, but Grotheer notes that it's worth the effort: qMRI is currently the only way to make the changing myelin content of the learning brain visible in humans. Drawing on five years of postdoctoral training at Stanford University, Grotheer established this line of research when she moved to Marburg University in 2021, where she initially worked as a Junior Group Leader and was appointed Professor in 2025.

With these tools in hand, Grotheer is now designing large-scale studies to investigate how learning-related changes in myelin unfold across the lifespan. One focus is infancy. As babies learn to crawl or begin reaching for objects, the brain undergoes remarkable changes. But the sequence of these events is not yet clear. "We want to assess the same babies multiple times to see whether it's myelin that increases first—or whether the new ability develops first and is then stabilized by myelin," says Grotheer.

Another focus is the transition from kindergarten to school, when informal, incidental learning gives way to more structured lessons. "It's a decisive turning point that is also reflected in the brain." In addition, the team is conducting training studies, where children, young adults, and older adults learn skills such as juggling or reading Chinese characters. This approach allows the researchers to compare learning-related changes in myelin content across different phases of life.

In the long term, the group's plans are even more ambitious: "It would be fascinating to track the same individuals across their entire lifespan." Ideally, this research would begin even before birth. But fetal imaging—MRI scanning during pregnancy—is among the most technically challenging areas of brain research: Fetuses move, the fetal brain is tiny, and the signals are difficult to interpret. Grotheer's team is developing specialized software tools to make it possible to analyze such challenging data.

Going forward, the results could have important applications—for example, in understanding learning disorders such as dyslexia or dyscalculia. "To know why some children develop differently, we first need to understand how typical brain development unfolds," explains Grotheer. Only then will it be possible to identify where development goes off track—and potentially design targeted support strategies to help.