She had a Piece of Her Brain Missing. It Wasn't Important
Early in February 2016, a woman read an article about two scientists at the Massachusetts Institute of Technology who were studying how the brain responds to music. The article was about how the brain responds to music. She told them, "My mind is interesting."
EG, who only wants to be known by her initials to protect her privacy, is missing her left temporal lobe, which is thought to help the brain process language. But EG wasn't quite right for what the scientists were studying, so they sent her to Evelina Fedorenko, a cognitive neuroscientist at MIT who studies language. It was the start of a relationship that turned out well. The journal Neuropsychologia just put out the first paper based on EG's brain, and Fedorenko's team plans to put out several more.
EG, who is in her fifties and grew up in Connecticut, is missing a big piece of her brain, but it hasn't changed her life much. She has a master's degree, has had a successful career, and speaks Russian so well as a second language that she has even dreamt in it. In the fall of 1987, when she was at George Washington University Hospital for a different reason, she had a scan of her brain done. That's when she found out that her brain was different from most. Most likely, she had a stroke when she was a baby. In that part of her brain now, there is only cerebrospinal fluid. EG didn't tell anyone but her parents and two close friends for the first ten years after she found out. She says, "It scared me." Since then, she has told more people, but her brain is still only known to a very small group of people.
She says that doctors have told EG many times over the years that her brain doesn't make sense. One doctor told her she should have seizures or shouldn't have a big vocabulary, and she says, "He was mad that I did." (As part of the study at MIT, EG's vocabulary score was in the 98th percentile.) EG says that the things that happened to him "pissed him off." "They said so many things and came to so many conclusions without doing any research at all," she says.
Then EG met Fedorenko. She didn't have any ideas about what she thought I could or couldn't do, she says. And for Fedorenko, the chance to study a brain like EG's is the dream of a scientist. EG was ready and eager to help.
Fedorenko's lab is trying to find out more about how the many parts of the brain that are thought to be important for learning and understanding language develop. The exact role of each hasn't been figured out yet, and it's especially hard to figure out how the system works. Fedorenko says, "We don't know very much about how the system develops." To find out, they would have to scan the brains of 1- to 3-year-olds whose language skills are still developing. "At that time, we just don't have the tools to look into kids' brains," she says.
Fedorenko knew that when EG showed up at her lab, this could be a great chance to learn how her remaining brain tissue has changed the way cognitive tasks are done. She says, "This case is a cool way to ask that kind of question." "It's just that sometimes you come across pearls that you try to use." Scientists don't often find people like EG who are willing to be poked and prodded.
The left side of the brain is where most people do most of their language processing. Some people have the same amount of work on each side of their body. Even less often, the right side of the brain does most of the work. Greta Tuckute, a doctoral student in Fedorenko's lab and the first author of the paper, says that if you're left-handed, you're "likely to wire up your language system in the right hemisphere." Scientists aren't sure why this is, but it seems to be the case.
The frontal and temporal regions of the brain are where most of the language processing happens. First, the temporal lobes grow, and then, when a child is about 5 years old, the frontal lobes grow. At this point, the language network is fully grown up. Because EG's left temporal lobe is missing, Fedorenko's team was able to find out if the temporal regions are necessary for the frontal language areas to form.
In their first paper about EG's brain, they wanted to know if her left frontal lobe, which was still in good shape, showed signs of language. If she did, that would mean that frontal language areas can form without a temporal lobe in the same hemisphere already being there. But if she didn't, it would mean that the temporal language areas are necessary for the frontal ones to develop.
The researchers used functional magnetic resonance imaging, or fMRI, to see what was going on in EG's brain as she did things like read sentences. As she talked, they watched her left frontal lobe for signs of language use. Then, they compared this brain activity to that of about 90 people whose brains were normal (similar data from people with intact left temporal lobes). In the end, they didn't find any, so they came to the conclusion that temporal language areas seem to be a must for the development of frontal language areas.
Still, they found that her left frontal cortex is perfectly able to support high-level cognitive functions. They proved this by having her do math problems while they watched her brain. They came to the conclusion that without her left temporal lobe, EG's right hemisphere seems to have taken over the job of processing language. It looks like a single hemisphere is enough to give her good language skills.