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Where does consciousness reside in the brain? New studies shed light

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Proposed in 2005 by pioneering genetic research, Nobel laureate Francis Crick, the theory suggested that consciousness resides in an area of ​​the brain known as the claustrum  (from the Latin  claustrum : “closed place” or “enclosure”). In the 1950s, the British researcher who helped decipher the helical structure of DNA, a discovery that earned him the Nobel Prize in medicine and opened up a new world of scientific knowledge, noted that the area of ​​the brain known as the claustrum appeared to be the central point between different areas of the human mind and proposed that this area was probably where human consciousness existed. Several competing theories of consciousness have since been put forward, while Crick’s has remained popular with many neuroscientists.

 

In the hope of measuring the veracity of the famous DNA researcher’s theory, using the most modern technologies that Crick certainly had at his disposal in ’62, a team from the University of Maryland School of Medicine decided to test it in the laboratory , demonstrating that instead of housing consciousness, the claustrum functions more like an internet router , transmitting complex signals between brain regions, and that consciousness does not reside in a single spot from the brain, but appears to occupy a much larger area than the claustrum.

The claustrum encodes signals from other areas

To test this theory against Crick’s, researchers at the University of Maryland first turned off the claustrum in a group of laboratory mice. As hoped, the mice did not lose consciousness, but continued to run normally. This result alone seemed to directly challenge Crick’s theory.

Subsequently, these same mice were given a variety of simple and complex tasks while the claustrum was still silenced. As theorized by University of Maryland researchers, the mice were able to complete the simplest tasks, but were hindered by the complex ones. This result seems to support their theory that the claustrum functions more like a modem and less like the seat of consciousness, giving Crick’s theory another blow. To determine whether these same findings were also manifested in human subjects Study lead author Brian Mathur, associate professor of pharmacology, collaborated with two other researchers, David Seminowicz, professor of pain and neural sciences in the UM School of Dentistry, and Fred Barrett, associate professor of psychiatry. and Behavioral Sciences at Johns Hopkins University School of Medicine. Together, the three researchers analyzed functional magnetic resonance imaging brain scans of healthy patients as they completed a variety of simple and complex tasks, just like the mice in the original study. As they had theorized, the researchers only saw the claustrum “light up” when the human subjects performed the complex tasks and not while performing simple tasks. As in previous tests, it appeared that Crick’s theory was wrong and that the new theory on the role of the claustrum was more accurate.

 

“The claustrum, therefore, receives executive commands from ‘major’ areas of the cerebral cortex (those that form complex thoughts) to generate ‘networks’ in the cortex,” the researchers explain in a press release. “Like a router, the claustrum sorts signals from other areas of the cortex and coordinates neural networks to work together to perform the different cognitive tasks we perform moment-to-moment in everyday life.”

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Important news for those suffering from Alzheimer’s, addiction and schizophrenia

Published in the journal Trends in Cognitive Sciences, the research not only sheds new light on an earlier theory of human consciousness, it may offer hope to those suffering from Alzheimer’s, schizophrenia and addiction. This is mainly because the dysfunction of the claustrum has been demonstrated as a basic component of these disorders. “Understanding how the brain flexibly forms and coordinates these networks — through the claustrum — is essential for treating the cognitive decline, which occurs in addictions, Alzheimer’s disease and schizophrenia,” said Mark T. Gladwin, Ph.D. University of Maryland, Baltimore. The researchers acknowledge that more studies are needed to explore these potential therapeutic strategies. However, in the light of the results obtained by the research team, it seems that Crick’s neurobiological theory of consciousness has almost fallen into prescription even though it was fundamental in arriving at these new awarenesses.

 
  • A role for the claustrum in cognitive control. (cell.com)

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