Neurophysiologists are trying to understand the nature of human consciousness by studying the claustrum - a tiny layer of gray matter deep in the brain. Despite the use of the most sophisticated technologies, they still cannot say how the “gray cells” transform the streams of scattered information from the organs of perception into a bright inner world. About the latest hypotheses of the formation of consciousness.
Behind the brain fence
In 2017, scientists from the Allen Institute of Brain Science (USA) discovered the longest neurons. To do this, they bred a special breed of laboratory mice that are sensitive to a certain drug that triggers the production of a green fluorescent protein in the rodents' body, which stained neurons in the claustrum. Thus, the researchers saw how neurons entangle the entire brain with their processes. Some were associated with almost all departments that receive information from the senses and are responsible for behavior.
The head of this study, Christoph Koch, suggests that claustrum serves as a source of consciousness. He expressed this hypothesis in 2005 in a paper co-authored with Francis Crick, the Nobel laureate who discovered the structure of DNA.
Crick and Koch likened the brain to a conductor-led orchestra. Musicians can play without it, but there is no coherence, a cacophony comes out. For the role of conductor, scientists suggested claustrum. Translated from Latin, this word means "hidden", in Russian the term "brain fence" is adopted.
A giant neuron entangling the brain of a mouse. A digital model of ten thousand brain slices.
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Network hub
The claustrum is a thin, irregular layer of gray matter in both hemispheres that is easily overlooked. It is located between the insular cortex and the putamen (basal nucleus). It is found in most mammals, but its purpose remains a mystery: due to its deep location, it is inaccessible for direct study.
The claustrum does not have a wide variety of neurons compared to the cerebral cortex. On the other hand, some of them stretch in branches to all parts of the cortex that read information from the organs of perception. Neurons transmit data to the claustrum and vice versa; information is exchanged with other departments responsible for movement, behavior, and memory.
The inclusion of the claustrum in the neural network, as well as the flows of information from the outside world passing through it, are exceptional. This prompted Crick and Koch to hypothesize that claustrum is the source of consciousness. They called on the scientific world to intensify work in this direction, especially since all the technologies for this have been invented. Thus, the phenomenon of consciousness, which until now has been exclusively occupied by philosophers and psychologists, has become the focus of attention of the natural sciences.
Flows of information from all parts of the cerebral cortex pass through the claustrum, it is associated with the areas responsible for memory / Illustration by RIA Novosti.
Internal homunculus
It has always been a problem for people to explain how a person perceives the external world and forms the internal one. I had to invent cunning schemes, the essence of which boils down to the fact that there are two substances in nature - spiritual and material.
Plato admitted a special world of ideas, to which the human soul belongs. Descartes spoke about the spirit that we perceive with the help of the pineal gland of the brain.
Those who prove that the spiritual world is more important than the material world are called idealists. Their extreme point of view is that, apart from the world of ideas, we know nothing, nothing outside of our consciousness exists.
Materialists insist that the spiritual world is the result of the work of the brain and our senses, which perceive the real world.
The dispute between idealists and materialists has been going on for more than two and a half thousand years, and finally, in our time, there is a chance to solve it using scientific methods.
Claustrum as a place of origin of consciousness is only a working hypothesis to test some observations by scientific methods. For example, the fact that a person cannot divide the stream of consciousness into parts and perceive them separately.
Sitting in the park on a sunny day, we are aware of everything at once and completely: warmth, light, bright colors around, sounds, smells. Someone has to process and combine the disparate electrical signals from neurons. This means that there is a special organ in the brain, for example, the claustrum, which coordinates the data coming out of the cerebral cortex from each sensory organ and converts them into a single stream that fills consciousness.
Christoph Koch - President of the Allen Institute of Brain Science (USA). He devoted more than ten years of his life to the search for the neurons of consciousness.
Searching for the neurons of consciousness
The idea that there is a cradle of consciousness in the brain suffers from serious flaws. Critics of this hypothesis rightly note that experiments on switching off consciousness through stimulation of claustrum with electrodes were carried out only on one epileptic patient and it is incorrect to extend the conclusions to healthy people. The high density of receptors in the claustrum that perceive the psychoactive substance salvinorin A, leading to loss of consciousness, is also not an argument, since they are also found in other parts of the brain.
American scientists observed 171 veterans of the Vietnam War with penetrating brain injuries, as well as patients after removal of a brain tumor. All patients periodically lost consciousness. Moreover, the frequency and duration of these attacks did not depend on whether the claustrum was damaged in patients.
Koch and his colleagues continue to search for the neural mechanisms that provide consciousness. The theory they rely on sees it as a by-product of the workings of such a complex networked organ as the brain.
In particular, this theory implies that no, even the most perfect computer program will possess consciousness. In his latest Scientific American article, Koch concludes:
"Consciousness cannot be calculated, it can only be built into the structure of the system."
Tatiana Pichugina