By age 20, AB had suffered four concussions, gotten viral meningitis, and been struck by lightning. “She’s unofficially the unluckiest girl alive,” says Kevin Mitchell, a neurogeneticist at Trinity College Dublin, who published a recent case study on AB, a pseudonymous subject. Her series of unfortunate events also ended up producing a scientific puzzle.

Because before all this, ever since she was a child, AB had been able to see colors with musical notes and perceive unique auras around people, the study reports. This mixing of senses is a little-understood phenomenon known as synesthesia. Synesthesia can come in many different forms, including colors that evoke sounds, words that evoke tastes, or even sounds that evoke touch. For AB, each insult to her brain—the concussions, the meningitis, the lightning—altered her synesthesia in different ways, both subtle and dramatic. Her synesthesia eventually returns exactly the same as before it went away.

No one had documented before such a case, where the perceived colors changed so much over time before returning to baseline. The brain is, weirdly enough, both malleable and unchanging.

As a child, when AB saw colors with musical notes, higher pitched notes were pastel; lower ones more solid. She could play by ear the tin whistle, flute, glockenspiel, marimba, and piano, perceiving out-of-tune notes as the wrong color. And when she saw auras around people, their colors were determined by the people’s personalities. She associated blue with loyalty, green with caring, red with power, and so on. But in her early teens, the study explains, AB had a couple of mild concussions that led to migraines. The prescription migraine medication she took erased all the color from her synesthesia for a time. Eventually, it came back.

At 19, AB got viral meningitis, an infection of the membranes around the brain. For a month thereafter, she could see colors with musical notes but they would be the wrong colors. She again recovered. But then she got another concussion, which moved the colors she saw from the center of her field of vision to the side. Yet another concussion made the colors more intense but somehow off. According to the study, it didn’t affect the actual colors she saw of objects in the real world, but the change in her synesthesia was still distressing. The colors AB perceived through synesthesia were as real to her as the colors of real objects; seeing different colors with the same musical notes was like waking up one day to find apples blue.

Things got really weird after she was struck by lightning two months later. This, understandably, increased her anxiety, and she started seeing strange colors like golds and silver along with colors that were possibly “not even real colors,” she told the researchers. Xanax calmed her, but it also muted the colors she perceived. Later, when she started getting seizures, medication again completely suppressed the colors. Her synesthesia returned to normal the next year, and the colors she associated with notes and people were the same as before the meningitis and lightning episodes.

Drugs can sometime induce synesthesia in non-synesthetes, so the idea that synesthesia can come and go is not surprising. “It’s almost in synesthesia folklore that synesthesia can weaken with certain types of drugs and depression,” says David Brang, a psychologist at the University of Michigan who studies synesthesia but was not involved in this case study. What’s remarkable, says Brang, is that AB’s color associations came back and remained consistent, despite all the medications and head trauma. In a second case also presented in Mitchell’s paper, a man referred to as CD lost his synesthesia for eight years when he started taking antidepressants for Seasonal Affective Disorder, only to have it return in full force when he stopped.

Synesthesia has two competing—though not mutually exclusive—explanations in neurobiology. In one, people with synesthesia have extra connections in their brains, connecting for example their auditory cortex with their visual cortex. In the second, everyone has these connections between different parts of the brains, but they’re usually unactivated. These connections may be disinhibited—as in un-unactivated—in people with synesthesia. The cases of AB and CD do not readily point to one explanation over the other. Perhaps the drugs and head trauma altered the wiring of their brains; perhaps it altered which connections were active. Perhaps both.

What the cases do neatly illustrate is the subjectivity of color, and by extension, of all our perceptions. If you can hear a note and see turquoise one day and hear the same note but see no color the next, then you have to conclude color is not intrinsic to the note. Even the color we see from real objects are our brains’ interpretations of wavelengths of light bouncing off that object. (Cough, The Dress.) That’s why AB could report perceiving colors that were “not even real colors.” “It’s a really fascinating insight into how the brain generates internally a representation of a color,” and how the brain could generate it wrong, says Mitchell.

For people with synesthesia, those colors they experience are also no different than the colors of real objects. Brang says he knows of people who stopped taking antidepressants for Seasonal Affective Disorder because they couldn’t stand losing their synesthesia. “It actually worsened their depression,” he says. “The loss of these color experiences had muted their world.” It was like losing a sense.

“Each person has their own unique window into the universe. Synesthesia is just a remarkable demonstration  of that,” says Peter Grossenbacher, a psychologist at Naropa University who has also studied people with synesthesia. Some of us have just looked through more than one window into the universe, not by choice but through (mis)fortune, drugs, and head trauma.