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The life of a young person in a coma due to a car accident was connected thanks to hearing.

Updated: May 29, 2022

Studying the "Study of Consciousness" (Stanislas Duanne) can further deepen your understanding of coaching theory.

I am studying to add a unique flavour to "unconscious rewriting".

This series of blog posts are my study notes. This time, the theme that follows the unconscious and conscious

I will write a "sign of consciousness".


This time, we will organize examples of research on hearing for how to monitor the consciousness of patients in a vegetative state.

It is straightforward to trigger a P3 wave audibly. The P3 faction is a large-scale brain wave shown when the brain's web is synchronized.

If you suddenly notice someone's cell phone ringing during a quiet classical music concert, your brain will have a sizeable P3 wave.

The method devised by the research team of Stanislas Duanne and others is to repeat the same sound regularly, such as "Bee-Bee-Bee ....", and then suddenly make a different sound such as "Boo".

If the subject is awake and focused, this strange sound causes brain waves, such as the P3 wave, which indicates the presence of consciousness.

It is not simply that we confirm brain wave was caused by sound intensity or other factors. The pattern was reversed, with "boo-boo-boo-boo ..." as the standard and "bee" as the strange sound. I tested it.

The research purpose was to conduct a test that evokes a conscious response to novelty. The research team has devised a new trick that contrasts local novelty with global novelty.

However, in this scenario, strange sounds resulted in not only P3 waves but also a series of early-stage brain reactions that represent unconscious processing. Only -00 milliseconds after the strange sound was emitted, the auditory cortex showed a significant response to the P3 wave.

This reaction is called "mismatch reaction" or "mismatch negative potential (MMN)" because it occurs at the crown as a negative potential.

This MMN is not a sign of consciousness, whether the person is focused, vague, reading a book, watching a movie, sleeping, or in a coma. The problem is that it is an automatic reaction that evokes the novelty of sound.

This reaction occurs in the unconscious process, and there seems to be no intervention of consciousness.

Instead, the human nervous system seems to have a novelty detector that works unknowingly.

This device compares the input stimulus with a series of past sound-based predictions for quick detection of strange sounds.

This kind of prediction is performed everywhere in the brain, and it seems that many cortical compartments also have simple neuronal networks for prediction and comparison. These actions are automatic, and only the results are of interest to you and your attention.

These effects mean that the measure of novelty does not work as a sign of consciousness.

The MMN response merely indicates that the auditory cortex has not lost its ability to detect novelty but does not prove that the patient is conscious.

In other words, this reaction is advanced, but it is an early-stage sensory action that functions out of consciousness.

The challenge for this study is to analyze subsequent brain events.

The research team has devised a new trick that contrasts local novelty with global novelty to conduct a test that evokes a conscious response to novelty.

Repeat this "Bee Boo Boo" five-tone sequence several times. The brain then becomes accustomed to the pattern of four "bees" followed by one "boo", which eliminates surprises at the level of consciousness. Still, the final deviant sound continues to trigger the initial MMN reaction.

The auditory cortex seems obsessed with predicting a continuous "beep" sound, unaware of the global pattern and considering it to be invaded by the final "boo" sound.

P3 waves are still closely related to awareness. The P3 wave disappears when the subject notices the global pattern of the five tones and is no longer surprised by the final deviant sound.

After this, you can break the regularity further by occasionally presenting the five sounds that do not include the strange sound "Bee Bee B Bee".

Such rare deviations cause P3 waves again. In other words, the brain classified the monotonous five sounds that I had heard before as novel.

The brain judges a sound that has worked before to be novel can be regarded as detecting the fact that it is different from the existing sound sequence that remains in the working memory.

The research team confirmed that the P3 wave could trigger without the initial unconscious reaction.

Moreover, if you let the subject count the deviation patterns, you can amplify them.

Experiments have shown that this local/global test works well.

Furthermore, the research team confirmed this widespread P3 wave response occurred in all healthy individuals, even after a concise recording session.

The auditory P3 wave disappeared when given a complex visual task and distracted but reappeared when the subject's freed his mind. In other words, the P3 wave did not appear in the subjects who overlooked the rule.

After the above study, Lionel Naccache has been regularly conducting this test at the Salpetriere Hospital in Paris.

Of the 22 vegetative patients, only two exceptionally showed P3 waves and then recovered to minimal consciousness within a few days.

There ia a case of young person who have encountered a terrible car accident.

The young man remained in a coma for three weeks and was completely unresponsive, inducing so many complications that the medical team wondered if treatment should continue.

But his brain was still responsive to global deviations.

Lionel wondered, "Isn't he temporarily in a sort of confinement and unable to express his remaining awareness?"

Lionel convinced the doctor that he could recover within a few days.

And, as he pointed out, the patient regained his consciousness ultimately.

As a result, the situation has improved dramatically, and he can now lead an almost everyday life.

The subject must memorize the five sounds in a row and compare them to the following five sounds emitted after a second or more.

The ability to remember information for a few seconds is also a testament to a conscious mind.

This feature is needed in two areas: "integrating individual sounds into a comprehensive pattern" and "comparing several comprehensive patterns."

The brain gets used to the final deviant sound as it repeatedly hears a series of "beebeebeeboo" sounds.

This strange sound still produces a novelty signal at the primary level in the auditory cortex, but it becomes predictive in the secondary level system.

After that, when you hear a series of sounds consisting of "bees" in all five sounds, this secondary level system is surprised.

The brain seeks to bypass the primary-level novelty detector and mobilize the capabilities of the secondary-level system, which is closely related to consciousness.

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