He human brain It is much more active during a state of unconsciousness than science believed until now. A study collected this Wednesday in the Nature magazine It shows that people continue to analyze the world around them even when they are completely anesthetized.
To reach this conclusion, a team of American researchers has recorded for the first time the neuronal activity of hundreds of individual neurons in the hippocampus (the part of the brain associated with memory) while patients were under general anesthesia in surgery. epilepsy.
They chose this surgery because it allowed them access to this specific part of the brain. And to measure neuronal activity in that area they turned to the new generation of ‘Neuropixels’, miniature silicon probes capable of recording the activity of neurons with great precision.
This technique allowed them to collect data on how the brain processes sound and language in a state of non-consciousness, such as general anesthesia.
The study began with patients exposed to repetitive tones occasionally interrupted by a different sound.
The researchers found that neurons in the hippocampus could distinguish these unusual tones and that this ability improved over time, suggesting that learning and neuronal plasticity continue during anesthesia.
Next, the scientists did a more complex experiment by playing short audio stories to the patients while recording their neural responses.
The result was that, despite the anesthesiathe hippocampus continued to process the language it heard in real time.
The neural activity showed the brain’s ability to differentiate parts of speech, such as nouns, verbs and adjectives, based on its own patterns.
Ability to anticipate in unconsciousness
And the researchers discovered something even more surprising: neural signals could predict the next words in a sentence.
“The brain seems to anticipate what comes next in a story, even without awareness,” says one of the authors, Sameer Sheth, a scientist in the Duncan Neurological Research Institute at Texas Children’s Hospital.
“This type of predictive coding is something we associate with being awake and attentive, but we have seen that it also occurs in an unconscious state,” says another author, Benjamin Hayden, professor of neurosurgery at Baylor School of Medicine in Houston, Texas.
“Our findings show that the brain is much more active and capable during unconsciousness than previously thought. Everything indicates that cognitive functions, such as language comprehension and prediction, do not require consciousness,” says Sheth.
Instead, consciousness might depend on broader coordination between brain regions, rather than activity within a single structure like the hippocampus.
Similarities with AI models
This activity also reflects the predictive behavior observed in the artificial intelligence (AI). “The brain’s ability to predict upcoming words is similar to the way large machine language models generate text,” says Sheth.
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This could be a step towards developing and perfecting new communication technologies, such as voice prostheses for people who cannot speak.
“Can we use these signals to implement and launch a voice prosthesis for some of the parts of the brain damaged by a stroke or injury? These are questions we can now ask ourselves.”say the authors.
They acknowledge, however, that their findings are specific to one type of anesthesia and may not be applicable to other states of unconsciousness, such as sleep or coma. Furthermore, this study has only analyzed one region of the brain, and it is unknown to what extent these processes are widespread in others.
“This work pushes us to rethink what it means to be conscious. The brain is doing much more behind the scenes than we scientists understand so far,” concludes Sheth.