Can you survive without a brain?

The brain is the organ that keeps us alive. What is known clinically and in law as death is often synonymous with brain death or brain death (although, believe it or not, there is still a prudent controversy surrounding what to consider dead or alive).

This is to say something like that no one is dead until our brain shows no signs of activity irreversibly. Due to this importance, the question of whether you can live without a brain seems somewhat absurd: basic homeostatic processes for life depend on it.

But here at our blog we like difficult questions to answer, especially those that seem to have an obvious answer that later turns out to be wrong. The question of life without a brain is one of them.

In this post we are going to answer the question ‘’Can you survive without a brain?’’ We will explain the role of the brain in maintaining life, its main functions and we will discover if it is possible to live without it.

Can you survive without a brain?

The human being boasts a brain. Anyone who is asked versed in neuroscience or not, about why humans are the most intelligent beings will probably answer that because our brain is more developed.

Perhaps the knowledgeable person will qualify her answer by saying that what characterizes our brain and what bases our intelligence is the expansion of the neocortex and the cortical associative areas.

We are so smart not because we simply have more but because we have better: we have more areas than are dedicated to processing information from various sensory modalities, from various dimensions of the environment, in conjunction with previously stored information, etc.

That is the standard answer, but there are cases that challenge it. We are going to present some of them here.

One can or cannot live without a brain: The minimum brain necessary for “life”

Let’s start with a simple statement. Following the subtitle above, the minimum brain necessary for life is none. We quickly realize this when we look at the thousands upon thousands of species of animals, plants, and other kingdoms that do not require a brain to be alive.

However, that answer is too simple. What interests us here is to know what is the minimum brain for life in species if they have one.

Most of us find it easy to tell the difference between someone living and someone dead. If we had to face the difficult task of determining if someone is in one state or another, our first impulse would probably be to see if they move, feel if their heartbeats, notice if they breathe, note their temperature or check their rigidity.

All of these “signs of life” depend largely on the survival of a couple of parts of our brain: the brainstem and the hypothalamus.

The brainstem

The brainstem thus functions as a kind of life support device. It can be said that the brain from the brain stem up “is not indispensable” to maintain the living body.

Of course, the ability to procure food, water and other necessary resources for our body is totally compromised if we have only a functional brain stem and not a fully functional brain, but as long as that structure continues to be healthy, strictly vital functions are kept and their owner is generally considered alive, in a vegetative state.

Individuals in this state are considered to be unaware of themselves or their surroundings but have signs of activity, such as wake-sleep cycles, and behaviors and reflexes such as opening their eyes, smiling, crying, yelling, biting, startling and others mediated by the activity of the motor nuclei found in this portion of the brain.

They are awake, so to speak, but are unable to perceive anything in their surroundings or themselves, and thus not respond to any of it (although neuroimaging studies seem to be challenging this idea).

In this state, patients are able to maintain their vital functions by themselves (breathing, regulating the heartbeat, intestinal functions, etc.), but they always need to be fed, washed and cared for. They cannot interact with their environment, much less speak, direct their eyes or carry out any other movement voluntarily.

The hypothalamus

Along with the brainstem, another brain structure is presented as important in maintaining this state of “life support”: the hypothalamus. In it are essential neurons to maintain vital autonomic functions such as thermoregulation.

Although technically it is possible to “survive” only with the brainstem, the work becomes very complicated when this other small structure is compromised by being able to incur high fever, excessive sweating or metabolic failures that complicate the prognosis much more.

The typical cases in which we can verify the “life support” function of these structures are those that derive from common causes of a vegetative state, such as brain injuries or cerebral infarcts.

However, there are two other approaches that reveal this distinguished work of the “minimal brain for life”: studies of animal decerebration and certain cases of anencephaly.

Decerebration and anencephaly

In decerebration studies, the front of the brain is removed. In this state, animals are capable of surviving several hours, being able to study some functions such as spinal motor reflexes, spinal and brainstem sensory-motor integration, cardiac and respiratory function, etc.

More striking are the cases of anencephaly in humans. Anencephaly is a malformation of the brain derived from a failure in uterine development that leads to the total or partial lack of this organ.

Those born with anencephaly usually lack a functional brain beyond the brainstem. In addition, they often have other craniofacial abnormalities and problems in other organs and systems, such as the heart or urinary system.

Although most children born with this malformation die on the same day of birth or within a few days, there are some cases that challenge this dire prognosis. The press reports on cases of anencephalic children who have been able to survive with a brain made up mainly of only the trunk for months and even years.

These children are considered to be not conscious (although some parents see authentic displays of conscious thought and will in their responses) but rather to be in a vegetative state.

The extraordinary case of the mathematical genius who was born without a brain

Can you live without a brain? What’s more: is it possible to be a genius and lead a normal life without this organ? Well yes, in fact the prestigious magazine Science asked: Is the brain necessary?

Now, understanding that the brain is necessary to live, it is time to learn about this case.

Twenty years ago Dr John Lorber was visited by a student at the University of Sheffield who had a minor headache.

The student was brilliant, with a very high IQ. The doctor perceived that the student’s head was a little larger than usual and to find out why he requested an additional examination.

Lorber ran a brain scan and was shocked: the boy had practically no brain. The only layer of brain tissue that he could see was about a millimeter. The student had a disease called hydrocephalus in which “the cerebrospinal fluid does not travel through the brain but inhabits the cranial cavity.”

What is surprising about this statement is that the loss of brain mass entailed, in this case, neither the loss of motor movements, nor that of sensory processes, nor that of memory or other cognitive functions.

All the investigations that Lorber carried out from this discovery warned that hydrocephalus was fatal in the first months of childhood and that if the individual managed to survive, he was seriously damaged.

However, the young man not only kept all his functions intact, but he lived a normal life and graduated with a degree in mathematics.

How is it possible that a person with almost no brain can live a normal journey and also have outstanding intellectual performance?

One of the theories that Dr. Lorber exposes is that “the brain has a great redundancy in functions and a small amount of brain matter can learn to represent the missing hemispheres.”

There are more theories, some of them are not accurate or enjoy unanimity in the scientific field, such as the one that defends that we only use 10% of our brain. What is true is that Dr. Lorber’s finding opens the door to all kinds of hypotheses and makes us question, without a doubt, what happens in the darkest corners of the enigmatic human intelligence.

The duality of the brain

This situation caused Lorber to investigate further, so that he could understand how it was even possible. Thanks to these investigations, he came to notice that his was not the first sighting of a case like this.

However, he took on the task of studying and documenting this biological peculiarity like no one before him.

Thanks to this, even with the strange nature of these events, Lorber managed to gather enough evidence from cases to create a classification. According to Lewin, Lorber separated these hydrocephalus survivors into four categories

The group where the fluid occupies 95% of the skull is only about 10% of the cases and, generally, those who are part of it have severe neurological disabilities. But, it is precisely in this group that individuals like Lorber’s student enter.

In fact, thanks to new research, we know that half of that percentage actually corresponds to people like that student, who not only can live without a brain in the traditional way, but also have IQs greater than 100 points and normal social skills.

Do we really need a brain?

The answer to this question remains yes. Indeed, in these particular cases, the brain as we know it is not present. However, instead they follow structures and components that fulfill their functions. Here simply the brain mass has been replaced by the accumulation of cerebrospinal fluid.

Lorber, at the time, admitted that the title of his research was a bit exaggerated, but that he considered it necessary to draw attention to the subject. Clearly, we cannot live without a brain; But, the idea of what we consider “a brain” might have to be expanded over time in view of these functional mutations that are being found among us.

FAQS: Can you survive without a brain?

How long can a person live without a brain?

As for fetuses that come into the world without frontal lobes, they only manage to survive a few days. However, in some cases, the little ones can live for a few years.

Can you live without a head?

No. You can’t live without a head.

What parts of the brain can we live without?

Since there are so many neurons in the cerebellum and it takes up so much room, without it it is possible to live, and a few people do. Nine known cases of cerebellar agenesis are known, a disorder in which this structure never grows.

What happens if there is no brain?

Brain death occurs when a person has the entire brain completely and irreversibly destroyed, with the cessation of all activity. It receives no blood or oxygen and dies.

Can brain be replaced?

No transplant of the human brain was ever performed.

In this post we answered the question ‘’Can you survive without a brain?’’ We explained the role of the brain in maintaining life, its main functions and discovered if it is possible to live without it.

If you have any questions or comments please let us know!

References

Lewin, R. (1980). Is your brain really necessary? Science, 210(4475), 1232–1234. https://doi.org/10.1126/science.7434023

‌Hydrocephalus Clinical Trials – Mayo Clinic Research. (2019). Retrieved December 13, 2020, from Mayo.edu website: https://www.mayo.edu/research/clinical-trials/diseases-conditions/hydrocephalus

‌Muckli, L., Naumer, M. J., & Singer, W. (2009). Bilateral visual field maps in a patient with only one hemisphere. Proceedings of the National Academy of Sciences, 106(31), 13034–13039. https://doi.org/10.1073/pnas.0809688106

‌Cleeremans, A. (2011). The Radical Plasticity Thesis: How the Brain Learns to be Conscious. Frontiers in Psychology, 2. https://doi.org/10.3389/fpsyg.2011.00086

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