After his injury, Padgett was drawing complex geometric shapes, but he didn't have the formal training to understand the equations they represented. One day, a physicist spotted him making these drawings in a mall, and urged him to pursue mathematical training. Now Padgett is a sophomore in college and an aspiring number theorist.
Padgett's remarkable abilities garnered the interest of neuroscientists who wanted to understand how he developed them.
Berit Brogaard, a philosophy professor now at the University of Miami, in Coral Gables, Fla., and her colleagues scanned Padgett's brain with functional magnetic resonance imaging (fMRI) to understand how he acquired his savant skills and the synesthesia that allows him to perceive mathematical formulas as geometric figures. (Synesthesia is a phenomenon in which one sense bleeds into another.) [Top 10 Mysteries of the Mind]
"Acquired savant syndrome is very rare," Brogaard said, adding that only 15 to 25 cases have ever been described in medical studies.
Functional magnetic resonance imaging measures changes in blood flow and oxygen use throughout the brain. During scans of Padgett, the researchers showed the man real and nonsense mathematical formulas meant to conjure images in his mind.
The resulting scans showed significant activity in the left hemisphere of Padgett's brain, where mathematical skills have been shown to reside. His brain lit up most strongly in the left parietal cortex, an area behind the crown of the head that is known to integrate information from different senses. There was also some activation in parts of his temporal lobe (involved in visual memory, sensory processing and emotion) and frontal lobe (involved in executive function, planning and attention).
But the fMRI only showed what areas were active in Padgett's brain. In order to show these particular areas were causing the man's synesthesia, Brogaard's team used transcranial magnetic stimulation (TMS), which involves zapping the brain with a magnetic pulse that activates or inhibits a specific region. When they zapped the parts of Padgett's parietal cortex that had shown the greatest activity in the fMRI scans, it made his synesthesia fade or disappear, according to a study published in August 2013 in the journal Neurocase.
Brogaard showed, in another study, that when neurons die, they release brain-signaling chemicals that can increase brain activity in surrounding areas. The increased activity usually fades over time, but sometimes it results in structural changes that can cause brain-activity modifications to persist, Brogaard told Live Science.
Scientists don't know whether the changes in Padgett's brain are permanent, but if he had structural changes, it's more likely his abilities are here to stay, Brogaard said.
The savant in everyone
So do abilities like Padgett's lie dormant in everyone, waiting to be uncovered? Or was there something unique about Padgett's brain to begin with?
Most likely, there is something dormant in everyone that Padgett tapped into, Brogaard said. "It would be quite a coincidence if he were to have that particular special brain and then have an injury," she said. "And he's not the only [acquired savant]."
In addition to head injuries, mental disease has also been known to reveal latent abilities. And Brogaard and others have done studies that suggest zapping the brains of normal people using TMS can temporarily bring out unusual mathematical and artistic skills.
Yet Padgett wouldn't change his new abilities if he could. "It's so good, I can't even describe it," he said.
It's always possible that having savant skills may come with trade-offs. In Padgett's case, he developed fairly severe post-traumatic stress disorder and obsessive-compulsive disorder, and he still finds it difficult to appear in public.
More From LiveScience:
This story originally appeared on LiveScience.com.
Copyright 2014 LiveScience, a TechMediaNetwork company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.