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The diagnosis of "signs of consciousness" has become more sensitive than a skilled clinician.

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".


The pulse test, which is a skilful combination of the two technologies of Massimini's TMS and EEG, organized in the previous article, seems to be applicable in all cases.

However, not every hospital can have a high-density EEG system capable of absorbing the strong impact of TMS.

Theoretically, this test should show signs of long-distance communication between brain regions in the dark or outside of external stimuli.

A constant flow of brain activity should flow between the prefrontal cortex and the parietal lobe, synchronizing distant brain regions.

This synchronous activity increases electrical activity in the middle (beta) and high (gamma) frequency bands, consuming large amounts of energy. So I want to find a way to detect it quickly.

PET scanners are advanced detectors that detect high-energy gamma rays and can measure glucose consumption in any part of the body.

Through PET scans, it is known that loss of consciousness reduces extensive metabolic activity in the brain.

This method yielded the following notable results:

Healthy individuals under anaesthesia or deep sleep showed a 50 per cent reduction in glucose consumption throughout the cortex.

In addition, decreased glucose consumption was observed in patients in a coma and vegetative states.

The degree of decrease in glucose consumption and even oxygen metabolism depends on the area of ​​the brain.

The frontal and parietal lobes are the most long-range projection-rich brain regions.

This fact can also be an important area for a conscious experience.

For the past 20 years, some patients have been unknowingly speaking occasionally.

This patient's neuronal activity and metabolism were confined to a small section of the language-controlling cortical region in the left hemisphere.

Maintaining consciousness requires broader (neuronal) communication, not just the cortical areas that govern language.

Unfortunately, the brain's metabolism itself is not sufficient as a basis for estimating the presence or absence of consciousness.

In contrast, and more importantly, many vegetative patients who have partially recovered and transitioned to a "minimal state of consciousness" do not exhibit normal metabolism.

High-precision images from modern MRI machines also do not provide a reliable predictor of consciousness.

It is not possible to accurately measure the circulation of information in the nervous system with anatomical or metabolic functional brain imaging.

As a next step, a move has begun to consider ways to detect the amount of synchronization itself between distant brain regions.

Nakarsch's team devised a program to calculate mathematical quantities called "wSMI (weighted Symbolic Mutual Information)" to measure the amount of information shared between two brain regions.

When they applied this program to patient data, they clearly distinguished between vegetative and non-vegetative patients.

Compared to conscious subjects, vegetative patients had significantly reduced information sharing. This phenomenon was true when focusing on a pair of electrodes at least 7-8 centimetres apart.

Simultaneous transmission (synchronization) of information between remote areas is a privilege of the conscious brain. Also, by measuring that direction, we found that the conversation in the brain was bidirectional.

The occipital lobe, a specialized and specialized area of ​​function, signals the parietal lobe and prefrontal cortex, which are generalist areas, and then signals back in the opposite direction.

Applying mathematical means to measure the amount of energy in various frequency bands, loss of consciousness results in activity loss in the high-frequency bands that characterize the processing of neural signals and neurons, typically during sleep and under anaesthesia. However, they found that the activity in the shallow frequency band, which is seen in the target, remains.

In addition, when they measured the synchronization of EEG vibrations, they found that the cortical region tends to harmonize the exchange of information between regions while conscious.

The measurements using these mathematical methods shed light on the phenomenon of consciousness from slightly different angles and provide a complementary perspective on the same state of consciousness.

Jean-Remi King has developed a program that fully automatically learns how to combine different measuring instruments to obtain an optimized prediction of a patient's clinical condition.

As a result, it became possible to make a highly accurate diagnosis using 20 minutes of EEG recording, and it was almost impossible to misdiagnose a vegetative patient as conscious.

Computer programs detected signs of consciousness in one-third. In contrast, clinical diagnosis indicated that they were in a vegetative state, but 50 per cent of them became conscious over several months. It has moved to a state that is clinically diagnosed as being.

This difference in predictive power makes a big difference in the results.

Automatic brain diagnostic programs can detect signs of consciousness long before they appear as behaviours or attitudes.

Diagnosis of signs of consciousness is now more sensitive than a skilled clinician.

The new science of consciousness is now bearing its first fruit.

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