I put my hand on a bishop and slide it several squares before moving it back. “Should I move a different piece instead?” I wonder to myself.

“You have to move that piece if you’ve touched it,” my opponent says, flashing a wry grin.

Fine. I move the bishop. It’s becoming increasingly obvious to me now — I’m going to lose a game of chess to a 12-year-old.

My opponent is Tanner Collins, a seventh-grade student growing up in a Pittsburgh suburb. Besides playing chess, Collins likes building with Legos. One such set, a replica of Hogwarts Castle from the Harry Potter books, is displayed on a hutch in the dining room of his parents’ house. He points out to me a critical flaw in the design: The back of the castle isn’t closed off. “If you turn it around,” he says, “the whole side is open. That’s dumb.”

Tanner Collins, Credit: Courtesy of Nicole Collins

Though Collins is not dissimilar from many kids his age, there is something that makes him unlike most 12-year-olds in the United States, if not the world: He’s missing one-sixth of his brain.

Collins was three months shy of seven years old when surgeons sliced open his skull and removed a third of his brain’s right hemisphere. For two years prior, a benign tumor had been growing in the back of his brain, eventually reaching the size of a golf ball. The tumor caused a series of disruptive seizures that gave him migraines and kept him from school. Medications did little to treat the problem and made Collins drowsy. By the day of his surgery, Collins was experiencing daily seizures that were growing in severity. He would collapse and be incontinent and sometimes vomit, he says.

When neurologists told Collins’ parents, Nicole and Carl, that they could excise the seizure-inducing areas of their son’s brain, the couple agreed. “His neurologist wasn’t able to control his seizures no matter what medication she put him on,” Nicole says. “At that point, we were desperate… His quality of life was such that the benefits outweighed the risks.”

Surgeons cut out the entire right occipital lobe and half of the temporal lobe of Collins’ brain. Those lobes are important for processing the information that passes through our eyes’ optic nerves, allowing us to see. These regions are also critical for recognizing faces and objects and attaching corresponding names. There was no way of being sure whether Collins would ever see again, recognize his parents, or even develop normally after the surgery.

And then the miraculous happened: Despite the loss of more than 15 percent of his brain, Collins turned out to be fine.

“We’re looking at the entire remapping of the function of one hemisphere onto the other.”

The one exception is the loss of peripheral vision in his left eye. Though this means Collins will never legally be able to drive, he compensates for his blind spot by moving his head around, scanning a room to create a complete picture. “It’s not like it’s blurred or it’s just black there. It’s, like, all blended,” Collins tells me when I visit him at home in January. “So, it’s like a Bob Ross painting.”

Today, Collins is a critical puzzle piece in an ongoing study of how the human brain can change. That’s because his brain has done something remarkable: The left side has assumed all the responsibilities and tasks of his now largely missing right side.

“We’re looking at the entire remapping of the function of one hemisphere onto the other,” says Marlene Behrmann, a cognitive neuroscientist at Carnegie Mellon University who has been examining Collins’ brain for more than five years.

What happened to Collins is a remarkable example of neuroplasticity: the ability of the brain to reorganize, create new connections, and even heal itself after injury. Neuroplasticity allows the brain to strengthen or even recreate connections between brain cells—the pathways that help us learn a foreign language, for instance, or how to ride a bike.

The fact that the brain has a malleable capacity to change itself isn’t new. What’s less understood is how exactly the brain does it. That’s where Behrmann’s study of Collins comes in. Her research question is twofold: To what extent can the remaining structures of Collins’ brain take over the functions of the part of his brain that was removed? And can science describe how the brain carries out these changes, all the way down to the cellular level?

Previous neuroplasticity research has shed light on how the brain forms new neuronal connections with respect to memory, language, or learning abilities. (It’s the basis for popular brain-training games meant to improve short-term memory.) But Behrmann’s research is the first longitudinal study to look closely at what happens in the brain after the regions involved in visual processing are lost through surgery or damaged due to a traumatic brain injury.

“We know almost nothing about what happens in the visual system after this kind of surgery,” she says. “I think of this as kind of the tip of the iceberg.”

So far, Behrmann’s findings are turning medical dogma on its head. They suggest that conducting brain surgeries in kids suffering seizures shouldn’t be viewed as the last available option, as it was for Collins. The surgery he underwent, while successful roughly 70 percent of the time, is still uncommon, which means that many people with similar brain tumors may be suffering unnecessarily. And depending on what Behrmann discovers, we may learn more than we ever have before about the brain’s capacity to bounce back.