Zoe Rain Bernstein was a happy, healthy, well-behaved 6-year-old until a car accident changed her life in an instant. Zoe was sitting in a booster seat in her father's pick-up truck in March when her dad lost control and the car slammed into a light pole. The impact left Zoe in a coma, and with a fractured skull. When Zoe woke up from her month-long unconsciousness, her mother Kelsie says, the little girl had a different personality. Can a brain injury really change the person you are inside? Here, a brief guide:

How badly was the Zoe hurt?

She suffered a brain injury, so she had to spend a month in the intensive care unit of the San Diego hospital where she was taken after the crash in La Costa, Calif. "She had to relearn how to eat, use the bathroom, brush her teeth, put on her shoes, everything," her mother said. "When she woke up out of the coma she couldn't talk. It was completely starting from scratch."

And in what ways did her personality change?

"Her personality is completely different," her mother says. Zoe has developed Attention Deficit Disorder, and she now has behavioral problems she never had before she was injured. The good news is that after relearning how to do basic tasks, Zoe is "functioning more like her peers" again, says Jeanne Sager at The Stir. The bad news is that her new mood and behavior problems have altered who she is, "and there's no sign that they'll go away."

Has this happened to other people?

Such dramatic changes are rare, but not unheard of, and sometimes they're even more dramatic. A 13-year-old Croatian girl suffered some kind of trauma — doctors, protecting her privacy, wouldn't discuss specifics — two years ago, and fell into a 24-hour coma. When she woke up, the girl, who had been studying hard to improve her limited German, suddenly spoke the language fluently. A macho, beer-swilling, 26-year-old British rugby player, Chris Birch, lapsed into a coma after suffering a stroke on the practice field in 2011. He awoke a changed man. "I realized I was gay," he said, "and I was okay with it."

Sources: Daily Mail, Patch, Pink Embassy, The Stir, Telegraph