The human brain is riddled with enigmas. Despite incredible advancements in technology and medicine, for instance, we still haven't pinpointed the cause of neurodegenerative diseases like Alzheimer's and Parkinson's.
And while the growing “brain training” industry (e.g., Lumosity) offers solace to our collective fear of lost memory and intelligence, the effectiveness of such programs to enhance memory, learning and even mood are hotly debated. Not to mention a bit expensive.
And so it was that I found myself in the office of Yi Zuo, Ph.D., nestled in the redwoods of UCSC. An associate professor of molecular, cellular and developmental biology, Dr. Zuo’s work runs along the cutting edge of the nervous system's unknowns, reaching into possible causes for neurological disorders and degenerative disease, as well as studying the way the brain rewires itself when learning something new.
Lumosity? Like everyone, Zuo had given it a whirl, ending it promptly when asked for her credit card information. “I definitely firmly believe that exercise, or activating the neurons constantly is good for your brain,” says Zuo. “And not only brain activities, like reading or puzzles, but actually working out is good for the brain too, because it brings oxygen into the brain.”
But Zuo is not an expert on Lumosity. She has more important things to do with her time; among them, studying glial cells in the neuromuscular junction—or the synapses that connect the nervous system to the muscular system. Derived from the Greek word for “glue,” these cells outnumber neurons in higher functioning animals (i.e., humans) and, you may have guessed, are a huge mystery. Until very recently, they were believed to exist solely to “glue” neurons together in the nervous system.
“It was generally believed that most neurological diseases come from the abnormal function of neurons,” says Zuo. “But recently, it has been found that glial cells in the brain play a very important role in the development and progression of many neurological diseases.”
Zuo thinks that glial cells, as important as they are for protecting neurons (and who knows what else), could be disrupting synapse connections—a process that occurs in both normal aging and neurodegenerative diseases. “The hope is that if we can understand the rules in the neuromuscular junction, we can apply similar rules in the brain,” says Zuo.
Offering up a rotation of beautiful drawings of neurons by the late Santiago Ramón y Cajal, “the Godfather of neuroscience,” and even sketching out the tree-like structures herself, Zuo passionately explains her latest study of synapse plasticity in the brain, which has shed light on the way we learn. By mapping out the formation and loss of new “spines” on the dendrites of mice as they learn a new motor skill, she's able to track the creation and loss of new synapse connections in the brain.
“What we’ve found is a huge spine increase in connections during the initial learning phase,” says Zuo. Curiously, on the second day, and during the consolidation phase, the amount of synapse loss also increases. “So that means that during the period of time we are learning, we are not actually making more connections in the brain, we are rerouting the brain. So we are making some new connections, but at an expense of losing some.”
The mystery of what we are losing when we learn something new intrigues Zuo. “It’s the reason many people say that the brain has a capacity well beyond what we are using,” she says.
And even while her studies focus on motor skills, she hopes her findings will inform learning strategies across the board. “Completely different brain circuits are involved in different types of memory,” says Zuo, who points out that we don’t actually know where those memories are stored in the brain. “If I want to learn English and French, then should I learn English for one year then learn French for one year? Or English one day, French one day—which is better? I still don’t know, but that is the hope behind the study,” says Zuo.