How Removing Half of Someone's Brain Can Improve Their Life

From the outside, Elena del Peral seems to be like any other high-achieving college senior. She goofs around the campus quad of Massachusetts’ Curry College with her classmates and posts pictures on Facebook of birthday drinks with girlfriends. She holds a philanthropic job at a childhood cancer foundation and is on the dean’s list. She's friendly, bright, and fit. Outwardly, perhaps the most provocative thing about her is that she’ll wear both a Yankees cap and a Red Sox jersey at the same time—a peacemaker among the long-standing rivals. 

But beneath her cap is one remarkable mind. Elena del Peral has only half a brain.

Image courtesy of Elena del Peral

Shortly after her birth in 1992, Elena’s parents started to notice that she was favoring her right side. By the time she was a toddler, she was solely using her left arm to shimmy along the floor, with her right arm tucked in to her chest. Within 18 months she began to suffer severe seizures, and at age two she had a massive tonic-clonic episode while vacationing in the Adirondack Mountains. Desperate to determine what was causing these intractable seizures and the hemiparesis, her parents, Sonya and Casiano, jockeyed from specialist to specialist throughout the northeast.

It turns out that Elena had suffered a left-sided congenital stroke in utero, which was sparking electric storms in her brain that spread from the diseased area across the corpus callosum—the great communicator between the two cerebral hemispheres—to the healthy right side of her brain. For the next four years, she took every epileptic medication in the book. They dulled her senses but didn’t stop the seizures.

At age six, del Peral underwent a battery of tests including MRIs, EEGs, and CAT scans. A team including neurologists and neurosurgeons pored over the results. They said her condition fit the criteria for a rare surgery that seemed radical but had yielded promising results in the past for people like her. It was called a hemispherectomy: “hemisphere,” half the brain; “-ectomy,” surgically removing it. In short, they wanted to remove half of Elena’s brain.

Dr. Howard Weiner, a pediatric neurosurgeon and professor of neurological surgery and pediatrics at the NYU Langone Medical Center and NYU School of Medicine, has been performing these types of surgeries on children for decades—including on Elena. He explained to mental_floss­ that when it comes to cases like hers, the normal part of the brain is impaired when it is bombarded by overly active impulses sent over from the damaged side. These children can suffer cognitive developmental impairment, partial paralysis, behavioral issues, social isolation, and a laundry list of other problems. Once that transmission is cut, the unharmed hemisphere can start functioning without all of that charged disruption.

Soon after, Weiner performed a left-sided hemispherectomy on Elena, removing the left half of her brain. Recovery after a hemispherectomy is very positive. With aggressive occupational therapy and physical therapy, children can usually lead normal, productive lives. Elena recalls to mental_floss, “Things suddenly got easy. I became smart. I made friends. I became social. I just need a little extra help.”

Her parents capitalized on her go-getter attitude and inner motivation. She attended special programs for children with disabilities and then attended Darrow School, a co-ed boarding school in New York, where her talents were fostered. Over the years, she excelled.


The first hemispherectomies—at least ones that patients actually survived—date back to the 1920s, when neurosurgery pioneer Walter Dandy removed entire halves of the brain to treat cerebral glioma, a type of brain tumor. In 1938, Canadian neurosurgeon K.G. McKenzie performed a similar procedure to treat a patient with left hemiplegia (paralysis on the left side of the body) and epilepsy; the patient's seizures eased after the right hemisphere was removed. Various techniques have been performed over the years, from cutting out small portions of the afflicted area to removing entire hemispheres.

In the past 25 years, the procedure has evolved, thanks to a better understanding of complications such as hydrocephalus, an abnormal accumulation of cerebral spinal fluid in the empty part of the brain cavity; improved surgical methods to prevent recurring seizures; accurate mapping and isolation of the unhealthy area; and a deeper knowledge of the brain’s plasticity. In fact, 2016 Republican presidential candidate and pediatric neurosurgeon Ben Carson revived the surgery in the 1980s at Johns Hopkins Hospital—the very hospital where Dandy operated.

But we have to look back to the 19th century to understand why we ever thought taking away half a patient’s brain might make her better off—and specifically to Phineas Gage, perhaps neuroscience’s most famous patient, who clued us in to the remarkable resiliency and adaptability of the human brain. In 1848, while he was working on a railroad-building site in Vermont, an explosion blasted a 43-inch tamping iron through Gage’s head, entering through his left cheek and exiting straight out of the top of his head.

Not only did Gage live to tell the tale, but he had a relatively normal life for another 12 years, working as a stagecoach driver in Chile before returning to San Francisco to live with relatives. Gage had some neurological deficits and major personality changes—he became an avid user of profanity and had little sense of social propriety, among other things—but various reports suggest that, all in all, his brain regained much of its function. In this studio portrait, Gage is said to be holding the iron rod that pierced his skull.

Gage’s case is only one of several historical incidents in which individuals sustained massive brain injuries yet largely recovered. Immensely complex, the brain is more than a collection of neurons and glial cells. It is the body’s primary controller, with highly specialized areas wired to command thoughts, movement, and action. For example, Broca’s area, located in the frontal lobe of the left hemisphere, controls the ability to speak. But the brain compensates. Despite the left side of her brain being gone, del Peral speaks without any difficulty—and quite eloquently.

Gage's and del Peral’s cases are prime examples of neuroplasticity, the brain’s ability to rewire networks and reorganize cellular or neural function to take place somewhere else.

“Language sets up shop by age two, three, and four, at which time we are learning how to speak,” Dr. Weiner says. “When the area that controls language is damaged, it can move. The earlier the insult, the more likely it is to move—the more plasticity.” That’s what happened in del Peral’s case. The left side of her brain was damaged in the womb, so language and motor function shifted to the right side before she was even born. At the time of her surgery, the left side of her brain, the source of her epilepsy, was doing more harm than good.


Hemispherectomies can reduce or eliminate seizures up to 89 percent of the time in children with certain neurological disorders, including infarcts (brain necrosis), malformations of the cortical development, Rasmussen’s encephalitis (an inflammatory condition that attacks only half of the brain), and Sturge-Weber syndrome (a vascular abnormality).

The trend now is to perform the surgery on younger children, and even babies, to take advantage of the brain’s plasticity as early as possible. For example, if the left hemisphere is removed around age 10 or after, the child will likely never speak again, as speech is already fixed.

Today, the operation can be much less invasive, with more vascularized brain left intact. In fact, surgeons are increasingly referring to the procedure as a hemispherotomy because they may not have to remove an entire half of the brain. In one diagnostic test, subdural electrode grids are surgically applied before the actual hemispherectomy in order to help neurologists and neurosurgeons map out the bad tissue. Once surgery begins and the brain is exposed, they work carefully from the inside out, following the corpus callosum to then functionally disconnect the communication link between the two halves of the brain. Highly technical microscopes and micro-surgical instruments—wielded with a lot of skill—are used to excise the problematic matter. Any hole that is left naturally fills in with cerebral spinal fluid, which protects the tissue left inside.

Disconnect is the key word,” says Dr. Weiner. “We went from resecting [complete removal] to simply disconnecting.”

By disengaging the damaged portion of the brain, the electrical storms stop traveling to the healthy side of the brain. Many patients like Elena can stop having seizures altogether and cease taking epileptic medications for good.

According to data collected by the Kids' Inpatient Database (KID) every three years from 2000 to 2009, 552 hospital admissions were documented for hemispherectomies in the U.S. during that time period, with a mean patient age of 6.7 years old. Currently, approximately 42 hospitals in the United States and 13 facilities abroad perform the surgery. The demand outpaces the supply; at the time he spoke to mental_floss, Dr. Weiner was en route to Panama to operate on children with intractable seizures.

Next spring, del Peral will graduate from Curry College, where she has made the dean’s list every semester since freshman year. “I have to work 10 times more than the average person, but it’s worth it,” she says. “No one has a story like mine. Living with half a brain? I don’t want this to define who I am.”

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Deutsche Telekom
This Virtual Reality Game Is Designed to Help Scientists Spot Dementia
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Deutsche Telekom

There’s a new reason to enter virtual reality, and it’s not to play ping pong or check the weather. A game designed to help diagnose dementia is coming to virtual reality, as CNET and the BBC report.

Sea Hero Quest, a game designed to test players’ ability to navigate, is now available for Oculus and Samsung Gear. Trouble navigating is one of the first signs of dementia, and the game (which was created by neuroscientists and funded by Deutsche Telekom) collects anonymous data on users’ ability to navigate through complicated pathways while captaining a virtual boat. It’s not designed specifically to be played by people with dementia, but rather to test the navigational skills of the population as a whole. The goal is to eventually be able to diagnose dementia far earlier than currently possible, perhaps by as much as 15 years.

Sea Hero Quest already claims to be the largest dementia study in history, with 3 million players so far. It can generate 15 times more data in virtual reality than in the mobile game, according to its developers, because it can capture eye-tracking movements and the movements of the boat within the game. Virtual reality can also support established tests developed for lab settings, like the often-used spatial learning task known as the Morris water maze.

The addition of virtual reality makes the process that much faster, adding a much larger dataset to what the scientists are already working on. They estimate that two minutes of gameplay generates the same amount of data as five hours in the lab.

This isn’t the first scientific foray into virtual reality. Researchers are also using it to explore sites for jaguar habitats, among other applications.

[h/t CNET]

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techbint, Flickr // CC BY 2.0
7 Famous Human Brains and Brain Collections You Can Visit
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techbint, Flickr // CC BY 2.0

We may be biased, but we think the human brain is pretty special. All this week, is celebrating this miracle organ with a heap of brain[y] stories, lists, and videos. It all leads up to Brain Surgery Live With mental_floss, a two-hour television event that will feature—yes—live brain surgery. Hosted by Bryant Gumbel, the special airs Sunday, October 25 at 9 p.m. EST on the National Geographic Channel.

Scientists have been collecting human brains ever since the techniques to preserve them were perfected in the mid 19th century. These days, many of those collections languish in basements and back rooms—thanks to imperfect preservation, lack of funding, and the decreased need to study actual specimens in an age where we can scan the brains of living patients with sophisticated techniques.

Fortunately, a few of the world’s most interesting brains and brain collections are on view to the public. Some of these collections were amassed to study neurological issues, while others were put together in a failed attempt to correlate brain size with race, sex, and intelligence. (Despite what many scientists once thought, humans with larger brains aren’t necessarily more intelligent.) Below, seven collections to help you create your own brain-based travel itinerary:


It seems fitting that you can see the brain of the man who became practically synonymous with the term during the 20th century: Albert Einstein. Since 2011, the Mütter Museum in Philadelphia has owned 46 slides of Einstein’s gray matter, stained with cresyl violet and mounted on glass slides. Neuropathologist Lucy Rorke-Adams donated them to the museum in 2011, after receiving them from a colleague in the 1970s. 

Ironically, Einstein might have balked at the idea of having his brain on display. He told friends and family he wanted to be cremated after his death, so no one would “worship at his bones.” Most of his body was cremated, but the pathologist on duty during his autopsy, a man named Thomas Harvey, decided to take the brain in order to study. He wanted to see if he could find any kind of neuroanatomical evidence of what make Einstein so brilliant. (Einstein’s family was furious, and Harvey only received retroactive permission to keep the brain for scientific analysis. He’s frequently been portrayed as a thief, but pathologists at the time often saved organs from autopsies.) Since then, it’s been a long, strange trip—and the research about whether Einstein’s brain had anything to do with his intelligence is still inconclusive. (Later this week we'll talk to Dean Falk, a researcher who studied Einstein's brain, about the evolution of the human brain.)  


The Musée Dupuytren in Paris’ Latin Quarter is crammed to the ceiling with hundreds of skeletons, wax moulages of skin diseases, and organs floating in glass jars. It’s also home to two of the most famous brain specimens in the history of science.

In 1861, the eminent French surgeon and anthropologist Paul Broca was the first to prove the doctrine of cerebral localization—the idea that a particular part of the brain could be responsible for a particular function. Broca’s autopsies on two aphasic patients, a Mr. Leborgne and a Mr. Lelong, showed a link between lesions in the third convolution of the left frontal lobes and speech loss (patients with the lesions couldn’t form articulate speech, but only repeat a few basic words or syllables). Broca’s research paved the way for modern neuroscience, and the speech production center of the brain is now named Broca’s Area.

Today the brains of Leborgne and Lelong sit alongside the other eerie anatomical oddities at the Musée Dupuytren, housed in what was once a 15th-century refectory. Even Broca’s own brain is sometimes said to be inside the museum, but staff claim that’s not the case; the whereabouts of the scientist’s own brain seem to be something of a mystery. For now, visitors have to be content with seeing the brains of his most famous patients.


Babbage's brain at the Science Museum in London. Image credit: Anne-Lise Heinrichs, Flickr // CC BY 2.0

English mathematician, inventor, and engineer Charles Babbage is often credited as the “father of the computer”—his Difference Engine No.1, invented in 1821, was the first successful automatic calculator, and his later “analytical engines” shared characteristics with today’s computers. Babbage is also frequently remembered for his work with Ada Lovelace, Lord Byron’s daughter, who some consider the first computer programmer.

Always a forward-thinker, Babbage also donated his brain to science. Today it’s on display in two places in London: half is at the Science Museum, and the other half at the Hunterian Museum in the Royal College of Surgeons. You can see a video of it here.


The Cornell Brain Collection was assembled by the noted anatomist Burt Green Wilder, creator of Cornell University’s anatomy department and founder, in 1889, of the Cornell Brain Society, devoted to collecting the brains of "educated and orderly persons.” Wilder hoped to show how such brains differed from those of criminals, minorities, the mentally ill, and women. Research showed they didn’t—at least not in ways observable by 19th-century technology.

At its peak, the collection included hundreds of specimens. Today, while 70 unidentified brains are housed in a Cornell basement, eight identified specimens are on display at the university’s Uris Hall alongside text explaining their biographies. Notable items include the brain of Helen Hamilton Gardener, an author, activist, and civil servant who donated her brain intending to prove that women were just as intelligent as men—and that their brains could be just as big.

Wilder even donated his own brain to the collection, and it remains on display. Also on view: the brain of murderer Edward H. Rulloff, turned a minty green thanks to poor preservation techniques.


 For decades, the brains in Yale’s Cushing Center collection languished in the basement of the Harkness Dormitory, where breaking in to see them was a ritual among medical students. Today, the brains sit in a well-appointed display that cost $1.5 million to create—a somewhat rare concentration of resources for a brain collection, which these days often stay hidden in storage rooms.

The brains were collected by Dr. Harvey Cushing, a neuroscience professor at Yale and a pioneer of modern neurosurgery, who willed them to the school upon his death. The most famous specimen belonged to Leonard Wood, who served as the personal physician to two presidents as well as Army Chief of Staff. Cushing successfully removed a large tumor from Wood’s brain in 1910, ending his seizures—one of the few such successful operations at the time. Sadly, Wood died in 1927 after an operation to remove a second tumor.

The brains are also notable for being displayed with before-and-after photos of the patients—less harrowing and more fascinating than they sound. Cushing’s journals, surgical instruments, and other specimens complete the exhibit.


The little-known Brain Museum at the Institute of Neurological Science in Lima, Peru, contains close to 3000 specimens, many of which show the marked effects of Alzheimer’s, alcoholism, tumors, or stokes. One of the star brains belonged to someone who suffered from Creutzfeldt-Jakob disease, sometimes called “human mad cow disease,” and which has been caused by some tribes eating human brains as part of their funerary practices. (On the other hand, at least one tribe appears to have developed a genetic resistance to the disease thanks to its former brain-eating ways.) The museum has been collecting specimens since 1947 and is one of the few large collections of brains that’s regularly open to the public.


The National Museum of Health and Medicine in Washington, D.C. holds eight different neuroanatomical collections—but the specimens are off-limits except for researchers with an appointment. However, if brains are your thing and you don’t have a PhD., you can still check out the museum’s Traumatic Brain Injury exhibit, which is open to the public. The exhibit features 30 specimens with a host of brain damage, including hemorrhages, blunt force trauma, and bullet wounds, as well as the surgical tools used to treat said injuries. It sounds fascinating, but maybe don’t visit right after lunch.


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