A man who lives without 90% of the brain, puzzled scientists


    Magnetic resonance tomogram of a patient with virtually no brain, but leading a normal social life. Photo: Feuillet et al./The Lancet A

    French man who lives a relatively normal and healthy life, despite the absence of 90% of the brain, forces scientists to reconsider theories about the biological essence of consciousness .

    Despite decades of research, experts still can not explain the phenomenon of consciousness - the fundamental way in which a person relates to the world. We know that this is something formed in the brain, on the basis of neurons. But how is consciousness preserved if the vast majority of neurons are missing?

    A clinical case first described in the scientific journal Lancet has been discussed in the scientific community for almost a decade.

    At the time of admission to the clinic, the patient was 44 years old, and until that time he did not do tomograms and did not know that he had practically no brain. The scientific article does not disclose the identity of the patient to maintain confidentiality, but scientists explain that he lived most of his life quite normally, without even knowing about his peculiarities.

    Brain scans man made almost by accident. He came to the hospital with a complaint of weakness in his left leg, but the doctor referred him to a tomogram. MRI results showed that the male skull is almost completely filled with fluid. There is only a thin outer layer with the medulla, and the inner part of the brain is practically absent.

    The illustration on the left shows a tomogram of a patient's brain, in which most of the skull is filled with fluid. For comparison, on the tomogram on the right is the skull of an ordinary brain without anomalies.



    Scientists believe that the patient's brain was slowly destroyed for 30 years as fluid accumulated — a process known as hydrocephalus (cerebral edema). He was diagnosed as a teenager and underwent shunting to restore movement of the liquor fluid, but at 14 he removed the shunt. Since then, the fluid in the skull has accumulated, and the brain is gradually destroyed.

    Despite this, the man was not recognized as mentally retarded. He does not have a very high IQ of 75, but this did not prevent him from working as civil servants, getting married and having two children.

    When the story of an unusual patient was published in the scientific press, she immediately attracted the attention of neuroscientists. It is surprising that a person with such anamnesis generally survived, and even more so was conscious, lived and worked normally.

    At the same time, this case allowed to test some theories about human consciousness. In the past, scientists have suggested that consciousness may be associated with various specific areas of the brain, such as claustrum (fence) - a thin (about 2 mm thick) irregular plate consisting of gray matter and located under the cerebral cortex in the depths of the white matter. Another group of researchers from Princeton University put forward the theory that consciousness is associated with the visual cortex. But the history of the French patient calls into question both theories.

    “Any theory of consciousness should be able to explain why such a person, who lacks 90% of neurons, still demonstrates normal behavior,” says Axel Cleeremans, a cognitive psychologist from the Free University of Brussels (Belgium). The scientist delivered a lecture at the 20th International Conference on the Scientific Study of Consciousness in Buenos Aires in June 2016.

    “Consciousness is a non-conceptual theory of the brain about oneself, obtained through experience — through learning, interacting with oneself, with the world and other people,” says Axel Cleeremans. In his scientific workthe scientist explains that the presence of consciousness means that a person not only has information, but also knows about the fact that he has information. In other words, unlike a thermometer that shows temperature, a conscious person simultaneously knows the temperature and takes care of this knowledge. The clereman states that the brain continuously and unconsciously learns to re-describe its own activity to itself, and these self-diagnostic reports form the basis of conscious experience.

    In other words, there are no specific regions in the brain where consciousness lives.

    Axel Cleeremans first published his theory in 2011. He calls it the “ radical plasticity clause ” of the brain. This thesis is quite consistent with recent scientific studies that showunusual plasticity of the adult brain , able to recover from injuries, “reprogram” certain areas for new tasks, restore consciousness and full working capacity.

    Cleremance theory can explain the case of a French man who retains consciousness in the absence of 90% of neurons. According to the scientist, even in this tiny brain, the remaining neurons continue to describe their own activity, so that the person gives an account of his actions and maintains consciousness.

    Our knowledge of the work of the brain is increasing every year. Despite the principle “No system can create a system more complicated than itself”, we gradually study the work of the central nervous system and learn to reproduce its functions. For example, just a few days ago, a scientific paper was published describing how blind mice partially restored vision by building up ganglion (nerve) cells in the retina of the eye - the part of the nervous system between the brain and the eye.

    All new discoveries are happening in this area. True, sometimes there is a strange feeling that the more we learn about the work of the brain, the more complex its device seems.

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