2023-06-19 01:06:58
There is no more complex organ than the brain. A cubic millimeter of cerebral cortex has 27,000 neurons and 1,000 million connections. According to the neurologist Luis Alfredo Villa, each neuron connects between 1,000 and 10,000 times with the others. Neurons are located in both cerebral hemispheres and extend through the brain stem and spinal cord to the nerves, where they innervate (reach) the muscles.
Passing this organ from one body to another, as is done with the heart or the kidneys, is an impossible odyssey and is a science fiction procedure because “we have more than 100,000 million neurons that connect to each other. This means that this organ generates a number of circuits that are interconnected, so a transplant would imply cutting them and reconnecting them again, but if they are cut, the neurons quickly deteriorate and die. This is almost impossible, the reconnection of the neurons would have to be one by one”, says Villa.
Neurologists are not closed to the possibility that in the distant future this could be possible with more advanced technological developments, but for now it is not. However, there is a question that science has asked: what would happen to the emotions and personality of the person who is transplanted?
The answer is key to understanding more about what this procedure would be: The donor is the one who remains alive, not the other way around, as happens with a heart transplant. In the end, it would not be a brain transplant but a body transplant.
“Each person is their brain. This organ brings with it a personality, a behavior, a way of expressing and relating. All the knowledge is stored in the organ, so it would actually end up being a body transplant, since this person would have a different body from before,” explained Andrés Villegas, professor and coordinator of the Neurobank of the Antioquia Neuroscience Group, attached to the Faculty of Medicine of the U of A.
It’s nothing more than science fiction. However, there are other types of procedures that have been explored in animals for decades, such as head and neuron transplants, the latter having more successful results because it is already done in people.
The head transplant
Transplanting just the brain organ is not the same as transplanting an entire head. In this procedure it is not necessary to cut the neural connections. It consists of the decapitation of a living being to insert its head into the body of another living organism. Although it sounds unreal, there are already some experiments in monkeys, dogs and rats that date back decades.
The first operation of its kind lasted 18 hours and was performed at a hospital in Cleveland, United States, where neurosurgeon Robert J. White transplanted the head of one monkey into the body of another. It was a surgery that was considered successful at the time, despite the fact that the animal had lived for only nine days and was paralyzed from the neck down because it could not connect the brain with the spinal cord of the receiving body.
The animal was able to hear, smell and even bite. It was considered an advance and until his death in 2010, the neurosurgeon fantasized about transplanting the head of a human. In fact, he had a candidate: Caraig Vetovitz, a young quadriplegic with organ failure.
This could not be accomplished because of their high cost and some television programs classified them as “Doctor Frankenstein and his monster.”
But the candidate always defended him: “He is not the type of person who is only going to change a head, he will do it if there is a high chance of full recovery. He knows what it is to be behind the eyes, because he sees it all the time, he sees the misery, ”he told the American newspaper Cleveland Scene in 1999.
There is loss of movement
A head transplant has not met with sufficient success because all trials end with the transplanted organism with no downward movement of the neck. In other words, they are left quadriplegic.
“The head transplant involves a spinal cord injury that leaves the animal quadriplegic, by sectioning the spinal cord at neck level along with the vagus and phrenic nerves, it has been impossible to reconnect it. Now that discussion has been fueled and there are certain advances in the procedure.
In experiments with animals, mechanical respiration has been improved and they have a longer lifespan, but it is still not an option for people who would require this type of procedure,” confessed doctor Andrés Villegas.
The doctor asks: what benefit is achieved with a transplant in which the person remains immobile from the head down? It is an ethical matter that is still discussed in bioethical meetings. For now, the findings could benefit people who are already quadriplegics who have significant systemic damage but whose brains are still in good condition. Surgery is not feasible because people are left with loss of movement and probably have problems breathing and swallowing, that is, getting food from the mouth to the stomach through the throat.
It may interest you: La 13 reaches the future: they create a metaverse inspired by the most famous commune in Medellín
neuron transplant
Dreaming of transplanting a brain or making a head transplant more viable may take time to be tested in humans, while neuron transplantation is a procedure that is already being done, even in Colombia. The neurologist Villa said that in his work he has transplanted neurons, with successful results, but that it continues to be an experimental field as well. The process consists of rebuilding brain circuits after brain damage. In this step, the stem cells that are responsible for creating new neurons every day are key, even if it happens only in certain regions of the adult brain.
“With stem cells, the possibility of inserting neurons is being explored so that the brain recovers from injuries that occur at the neurological level, but it must be taken into account that neuronal connectivity is complex and takes place as we learn new skills” Villegas said.
This type of procedure, the neurologist Villa says, is done mainly for patients who have post-trauma accidents and diseases that damage neurons such as Parkinson’s, where the neurons that produce dopamine die slowly and their absence causes chaos in the brain circuits, causing problems. engines.
To repair the damage, transplants of neurons that produce dopamine have been done and there have been successful results because symptoms improve. “This cell therapy benefits diseases such as Parkinson’s, in fact, it could be the best treatment option in some cases,” added Villegas.
The brain also has the ability to recover, it is resilient. This ability is known as plasticity. It modifies connections between neurons and new connections are formed and others are removed allowing a person to recover from brain injury.
“If a person was injured, for example, had a stroke or a specific lesion in a focal area, the cells involved in that region lose their faculties and others adopt the functions that were lost. It is learning again with new cells”, concluded the doctor.
#Brain #transplant #dream #science #fiction