"What do you just think?": What will happen if the brain will lose one hemisphere
What will happen to a person if he will have only half of the brain? It seems to us that the answer is obvious. The body that is responsible for the most important processes of life is difficult, and the loss of its meaningful part can lead to terrible and irreparable consequences. However, the possibilities of our brain still surprise even neurobiologists. Biopsychologist Sebastian Oklenburg shares the results of the study, which sound like a tie of the plot of a fantastic film.
Sometimes, to save human life, doctors have to go to extreme measures. One of the most radical procedures in neurosurgery is considered hemisferctomy, a complete removal of one of the hemispheres of the brain. This procedure is performed only in very rare cases of hard epilepsy as the last attempt to help the patient, when all other options failed. When removing the affected hemisphere, the frequency of epileptic seizures, each of which threatens the patient’s life, is radically decreased or comes at all. But what happens to the patient?
Biopsychologist Sebastian Ocelenburg knows a lot about how the brain and neurotransmitters affect the behavior, thoughts and feelings of people. He tells about a recent study that helps to understand how the brain can work when only half remains from him.
Scientists investigated brain networks in several patients, each of whom one hemisphere was removed in early childhood. The results of the experiment illustrate the brain ability to be reorganized even after serious damage, if this damage occurs at a young age.
The authors used the neurobiological technique of functional magnetic resonance tomography (MRI) at rest. With this study, the brain of participants is scanned with the help of an MRI scanner, the device, which today is in many hospitals. The MRI scanner is used to create a series of pictures of body parts based on their magnetic properties.
Functional MRI is used to create brain images in the process of performing a specific task. For example, the subject says or moves his fingers. In order to create a series of images at rest, the researcher asks the patient to lie in the scanner motionless and do nothing.
Nevertheless, even without any specific tasks, the brain exhibits great activity: for example, in this state we dream, and our mind "wanders". Identify which areas of the brain are active in inactive condition, researchers were able to find its functional networks.
Scientists examined the networks at rest in the group of patients who, in early childhood, an operation was made to remove half of the brain, and compared them with the control group of participants who worked both half of the brain.
Our incredible brain
The results were truly amazing. It would be possible to expect that the removal of half the brain seriously violates its organization. However, networks that have suffered such an operation of patients looked surprisingly similar to network control groups of healthy people.
Researchers identified seven different functional networks – for example, related to attention, visual and motor ability. In patients with remote half brain, the relationship between the areas of the brain within the same functional network was surprisingly similar to the indicators of the control group with both hemispheres. This means that patients demonstrated the normal development of the brain, despite the absence of one half.
However, there was one difference: patients had a marked connection between various networks. These reinforced links seem to reflect the processes of cortical reorganization after removing half of the brain. Thanks to more durable bonds between the rest of the brain parts, these people seem can cope with the loss of another hemisphere. If the operation is carried out at an early age, the patient, as a rule, remains normal cognitive functions and intelligence, and it can lead the usual life.
It is even more impressive if you consider that brain damage at a later age – for example, under stroke – may entail serious consequences for cognitive abilities, even if only small parts of the brain are damaged.
Obviously, such compensation occurs far away and not at any age. However, the results of the study make a significant contribution to the study of the brain. In this area of knowledge, there are still quite a lot of white spots, which means that neurophysiologists and biopsychologists have a wide field of activity, and writers and screenwriters – scope for imagination.