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How the brain can rewire after half of it has been removed



Shortly after the birth of her first son, Monika Jones learned that he had a rare neurological disorder that made one side of his brain unusually large. Her son Henry suffered hundreds of seizures every day. Despite the high doses of medication, his small body worked like a rag doll as one episode passed into another. He needed multiple surgeries, beginning at 3 1/2 months, which eventually led to a complete anatomical hemispherectomy or removal of half of his brain when he was 3 years old.

The procedure was first developed in the 1

920s treating malignant brain tumors. But its success in children with brain malformations, intractable seizures, or illnesses where the damage is limited to half of the brain has amazed even experienced scientists. After the procedure, many children can walk, talk, read and do everyday tasks. About 20 percent of the patients who use the procedure find work as adults.

Studies published in the journal Cell Reports on Tuesday suggest that some individuals recover so well from surgery in the brain as a result of restructuring in the remaining half of the year. Scientists identified the various networks that close the gap for the distant tissue, with some specialists in the brain learning to work like generalists.

"The brain is remarkably plastic," said Dorit Kliemann, a cognitive neuroscientist at the California Institute of Technology and the first author of the study. "It can compensate for the dramatic loss of brain structure, and in some cases, the remaining networks can support an almost typical perception."

The study was funded in part by a charitable organization that Mrs. Jones and her husband had founded advocates for others who need surgery to stop seizures. The results of the study may encourage those looking for hemispherectomies beyond early childhood.

When persons came with hemispherectomies to scan their brains for the study, they seemed to behave like other typically developed adults, dr. To shake Kliemann's hands and to make small talk. The results of magnetic resonance imaging (MRI), however, showed that the subjects of childhood had half their brain removed.

"Whenever we looked at their brain scans, we said, 'Wow, that brain really should not. I can not work,' said Ralph Adolphs, a cognitive neuroscientist at the California Institute of Technology and co-author of the study. "If you take another system with a set of parts whose functions all depend on each other, like the heart, and you divide it in half, it will not work, take my laptop and cut it in half, it will not work. "

Most brain networks use both hemispheres to function. For example, facial recognition affects both sides of the cerebral cortex. Other abilities, such as the ability to move one's limbs, are processed from opposite sides of the brain. The right hemisphere controls the movement of the left side of the body, while the left hemisphere controls the right arm and the right leg.

said Marlene Behrmann, a cognitive neuroscientist at Carnegie Mellon University who was not involved in the study. Instead, the researchers found that the type of compounds remained the same in individuals with only one hemisphere. Different regions responsible for processing sensorimotor information, sight, attention, and social messages strengthened the existing connections and communicated more frequently than normal brains.

It was almost as if parts of the brain that would normally have been specialized, eg. As a trumpeter, he had spoken with the rest of the band and assumed additional responsibility to play percussion as well. Behrmann said. "Your brain networks seem to be multitasking."

The results are encouraging for researchers and families trying to understand how the brain adapts and works after a hemispherectomy.

is a really long-lasting phenomenon, "Dr. Ajay Gupta, a pediatric neurologist at the Cleveland Clinic, who accompanied nearly 200 children after the operation.

Until recently, the scientific consensus was that hemispherectomy can best be performed at a very young age, before a child is 4 or 5 years old. In this way it can regain its normal function with age. While neuroplasticity is more pronounced in early childhood, the new study suggests that the surgery should not be discontinued after an arbitrary end date, said Drs. Gupta. Adults in the study underwent hemispherectomy at the age of 3 months to 11 years.

One factor that may play a more important role in patient outcomes is the age at which seizures occur. The operation is still considered the last resort after medical treatment. However, if the duration of seizures and the resulting brain damage can be limited, patients can become more functional again.

"The other hemisphere already needs to take on additional responsibilities before patients are treated," said Lynn K. Paul, a neuroscientist at the California Institute of Technology and co-author of the study . "This continues to happen if you remove the damaged hemisphere. So we really want to protect the working hemisphere.

The eight-hour operation is not without risks. The brain tissue must be removed carefully and in sections, Dr. Gupta. If even a small fiber is left behind, it can lead to renewed seizures and affect the healthy side of the brain. There is also a risk of persistent headache and fluid retention in the brain.

After the operation, children on the opposite side of the operation in the hands and arms become considerably weaker. Your view will be blocked on this page and you may also lose the ability to detect where sounds are coming from. "There are some things that definitely require a higher level of rehabilitation and learning. For example, reading and writing and math, "Dr. Gupta.

In many cases, however, these capabilities have already been compromised by the underlying diseases.

Mrs. Jones is confident that further research and the pursuit of more patients over time will help researchers understand the development and organization of the brain so that information can provide targeted interventions for a wide range of individuals with brain injury and disease.

Now she is happy that her son can go it alone, communicate with an iPad and eat without a feeding tube.

"He really loves McDonalds," she said.


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