Part of what makes aging such a downer is the idea that our brains lose that flexible, footloose and fancy-free quality that enabled it to quickly soak up knowledge and learn new skills at the pace of a virtuoso when we were younger. But a new study, recently published in the journal Cell Metabolism, has discovered that some regions in the adult brain actually still display a “childlike” quality that enables the formation of new connections, which is important for retaining new information, such as the skills to play the piano, even at later ages.
Researchers from St. Louis’ Washington University School of Medicine and Seattle’s Allen Institute for Brain Science discovered that genes that play a role in building new connections between nerve cells continue to be highly active in certain regions of the brain. These same genes are also typically active in young, burgeoning brains, implying that the brain is still encoding new memories and skills long after it stops growing well into our 20s.
“We already knew that the adult human brain generally has more activity among these genes when compared with other closely related species, including chimpanzees and monkeys,” first author, Dr. Manu Goyal of Washington University, explained in a press release. “Our new results connect this activity to a form of energy production known to be helpful for building biological structures, such as the new nerve cell branches needed to add connections in the brain.”
Previous work by the senior author of the study, Dr. Marcus Raichle, identified these regions of exceptionally high energy production in the brain and was even able to deduce how these areas generated their outstanding vigor. The process is an alternative way to make energy called aerobic glycolysis, which happens to be more pervasive in the brains of young children and a better source of energy for rapid growth in the brain. According to Goyal, aerobic glycolysis in the brains of young children makes up for 30 to 40 percent of all the glucose that gets metabolized in their body.
The line of research was triggered by a surprising spark: cancer. “Aerobic glycolysis happens to be the form of sugar consumption favored by cancer cells and other rapidly growing cells,” Goyal explained in the release. “This made us wonder if the brain regions that use aerobic glycolysis were also those that had the most childlike gene activity, namely those that help form new brain cell connections.”
Goyal and colleagues’ hunch proved to be correct; a meta-analysis of previously published studies revealed that these high energy brain regions showed more youthful gene activity than other areas while an additional 100 genes were also found to be working on overdrive. “Even in adults, there are parts of the brain that still are rapidly changing and adapting, and that’s likely why aerobic glycolysis continues to be used in the adult brain,” Goyal said.
Interestingly, the authors’ analysis also found that when the brain is in an undemanding “resting state” the highest levels of aerobic glycolysis occur in regions that are known to be most active in the absence of any attention-demanding, goal-directed tasks i.e. when the mind is allowed to wonder. The researchers are now assessing these metabolic findings through a therapeutic lens and seeing whether impaired aerobic glycolysis could play a role in neurodevelopmental problems, such as autism, as well as symptoms that arise after brain injury and neurodegenerative disorders.
Source: Goyal, M. et al. Aerobic Glycolysis in the Human Brain Is Associated with Development and Neotenous Gene Expression. Cell Metabolism 19, 49–57, January 7, 2014