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A woman grew up without left temporal lobe

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.

The Curious Hole in My Head - The New York Times
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.

brans scans

An MRI image of EG's brain.

Photograph: Evelina Fedorenko, Greta Tuckute/Brain and Cognitive Sciences
The fact that EG's unique brain has such a small effect on her day-to-day life shows how much we can do without big parts of our brains. Fedorenko talks about a surgery called hemispherectomy, which is done on children with epilepsy who don't get better with medicine. The procedure involves taking out the half of the brain where the seizures are happening. These children have been shown to be able to think normally after the surgery. Fedorenko says, "If you can take away half of your brain and still be fine, that means there are a lot of parts in our brains that aren't needed." "There seems to be a lot of stuff in our brains that does the same thing twice, which is a pretty good way to build a system from an engineering point of view."

The truth is that when the brain gets hurt, it often finds a way to fix itself. Ella Striem-Amit is a cognitive neuroscientist at Georgetown University. She knows a lot about this. She looks at how the brain changes when it loses a sense, like when a person is born blind or deaf. "What's amazing about this patient and others like him who were born missing big parts of their language system or other systems is how well they can make up for it," she says.

Specifically, if the problem starts when the person is young, when neuroplasticity is stronger, another part of the brain will usually just take over the task of the missing part by making new neural connections. Striem-Amit says, "There has been a lot of research over many years that shows how much more flexible the brain is when you are young."

It might be too soon to draw any conclusions from what a single person saw. In recent years, studies of individuals have gotten a bad name because the results of smaller studies can be random. In research, there has been a big shift toward the idea that bigger is better. But, for the most part, case studies are what made modern neuroscience possible. Scientists learned in 1861 from Broca's patient which part of the brain controlled speech. The patient H.M.'s brain showed how memories are stored in the brain. And Phineas Gage, a railroad worker who had an iron rod driven straight through his brain in 1848 and whose personality changes after the injury are thought to have shown for the first time that some functions are associative. Striem-Amit says that all of the most important discoveries that have led to our understanding of the brain began with case studies. "Without those special cases, we wouldn't have been able to figure out as much as we did or say anything about cause and effect."

Fedorenko says that looking at high-quality data about an individual instead of a map of a group is like "using a high-precision microscope instead of looking with a naked myopic eye, when all you see is a blur." Fedorenko says that if a n=1 method is used carefully, it can lead to groundbreaking insights, like in the case of EG. She says, "We can learn a lot from situations where something is a little bit different." "It seems like a waste not to take advantage of these natural events."
Striem-Amit agrees that it's important to study unique cases. "There is a trend toward big data, and we need to stress the importance of deep data, which is studying very detailed experimental designs of individuals to learn how each brain is organized."

Fedorenko's lab hopes to learn a lot more from EG's brain in the future. In a preprint that was posted online last month but hasn't been peer reviewed or published by a journal yet, they looked at a part of the brain called the "visual word form area," which is thought to be in charge of decoding the written forms of words. Neurotypical people have this area in the left ventral temporal cortex, but EG has it all over her brain, and Fedorenko says she is a "really good, fast reader." They are also looking at how EG's missing temporal lobe affects her hearing for a future study.

Fedorenko says that EG's sister is missing her right temporal lobe, but she doesn't seem to be affected by it. This suggests that the missing brain regions are likely caused by a genetic link to the early childhood strokes. Next, the team wants to use both EG and her sister, who has also agreed to be studied, to try to figure out why most social and emotional processing happens in the right side of the brain. In fact, everyone in the family is taking part. A third sibling and EG's father have also had their brains scanned. It turns out that each of them has two intact temporal lobes, or what EG calls a "boring brain." Soon, a fourth brother or sister will be scanned. EG didn't think anyone would want to study her for a long time, so she is just happy that the field of neuroscience has been able to learn something from her brain. "I also hope that it will help change the way people think about people with different brains," she says.

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