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Many vegetative patients are actually 'covertly conscious'

This unsettling new understanding of vegetative patients raises medical ethics issues.

Photo by Daan Stevens on Unsplash
  • For a long time, doctors assessed whether patients were in vegetative states through behavioral tests.
  • However, brain scans have revealed that some of these patients are actually in a state of "covert consciousness."
  • Covertly conscious patients are aware of their surroundings, but cannot respond to external stimuli.


In 2005, a 23-year-old woman was caught in a traffic accident that gave her a traumatic brain injury. Her doctors diagnosed her as being in a vegetative state — that is, absent of awareness and responsiveness, but still able to keep her heart pumping, her lungs breathing, to fall asleep and become awake, and so on.

Five months after her accident, however, researchers conducted an experiment showing that she had not completely lost her conscious awareness. Using an fMRI, researchers asked her to imagine playing tennis or walking through her house. Though the patient had been unable to respond to any other cues, the fMRI showed that her brain lit up when asked to imagine these things, suggesting that she was, in fact, conscious to some degree — just unable to move her hands or open her eyes on command. This patient would be the first time that signs of consciousness were detected in an ostensibly vegetative state using fMRI.

The trouble with diagnosing vegetative states

Since then, more and more cases of this sort have come to light. In fact, over the years, researchers estimate that around 10 to 20 percent of supposedly vegetative patients in fact experience what's called "covert" consciousness. Patients with covert consciousness do not respond to behavioral tests of awareness yet show brain activity related to awareness. It is important to note that covertly conscious patients do not fail to respond to behavioral tests because they are paralyzed. Instead, they fail to respond because the parts of their brain that respond to stimuli are damaged — they can still move, and sometimes will, but typically not in response to external stimuli.

After a traumatic brain injury that lands a patient in an ostensibly vegetative state, many clinicians assume a poor prognosis. As a result, many families decide whether to keep their loved one on life support or to withdraw it within the first three days after admission.

"The problem with severe brain injury," said neuroscientist Nicholas Schiff in The Scientist, "is that you have people who all look the same who could have very different trajectories of recovery over time, response to treatment, or already achieved level of recovery." Better diagnostic tools are needed to "sort the variance and also to figure out who we should look at more closely and immediately."

A better method

A healthcare professional administers an EEG.

BSIP/Universal Images Group via Getty Images

Patients with covert consciousness have been shown to recover at higher rates than those in persistent vegetative states even though they appear to be the same from the outside. Deciding to pull the plug on a loved one is never an easy task, but the uncertainty of whether or not they are truly beyond help makes it even more difficult.

Fortunately, researchers are working on ways to improve diagnosing these cases of covert consciousness. While fMRIs were the original way that researchers detected covert consciousness, applying them in critical care settings can be challenging. Electroencephalographs (EEGs) are likely to be far more useful as a diagnostic tool.

The first large-scale demonstration of using EEGs to diagnose cases of covert consciousness was recently published in the New England Journal of Medicine, where doctors asked patients to move their hands (which neither vegetative nor covertly conscious patients can do), and then used machine learning to decipher their EEG readings to identify brain activity in response to the commands. Twelve months later, 44 percent of those patients who were detected to have some brain activity were no longer vegetative and could function independently compared to just 14 percent of patients with no sign of activity in the EEG.

"This is very big for the field," Nicholas Schiff told The New York Times. "The understanding that, as the brain recovers, one in seven people could be conscious and aware, very much aware, of what's being said about them, and that this applies every day, in every I.C.U. — it's gigantic."

Hints of the 4th dimension have been detected by physicists

What would it be like to experience the 4th dimension?

Two different experiments show hints of a 4th spatial dimension. Credit: Zilberberg Group / ETH Zürich
Technology & Innovation

Physicists have understood at least theoretically, that there may be higher dimensions, besides our normal three. The first clue came in 1905 when Einstein developed his theory of special relativity. Of course, by dimensions we’re talking about length, width, and height. Generally speaking, when we talk about a fourth dimension, it’s considered space-time. But here, physicists mean a spatial dimension beyond the normal three, not a parallel universe, as such dimensions are mistaken for in popular sci-fi shows.

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Does conscious AI deserve rights?

If machines develop consciousness, or if we manage to give it to them, the human-robot dynamic will forever be different.

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  • Does AI—and, more specifically, conscious AI—deserve moral rights? In this thought exploration, evolutionary biologist Richard Dawkins, ethics and tech professor Joanna Bryson, philosopher and cognitive scientist Susan Schneider, physicist Max Tegmark, philosopher Peter Singer, and bioethicist Glenn Cohen all weigh in on the question of AI rights.
  • Given the grave tragedy of slavery throughout human history, philosophers and technologists must answer this question ahead of technological development to avoid humanity creating a slave class of conscious beings.
  • One potential safeguard against that? Regulation. Once we define the context in which AI requires rights, the simplest solution may be to not build that thing.

A new hydrogel might be strong enough for knee replacements

Duke University researchers might have solved a half-century old problem.

Lee Jae-Sung of Korea Republic lies on the pitch holding his knee during the 2018 FIFA World Cup Russia group F match between Korea Republic and Germany at Kazan Arena on June 27, 2018 in Kazan, Russia.

Photo by Alexander Hassenstein/Getty Images
Technology & Innovation
  • Duke University researchers created a hydrogel that appears to be as strong and flexible as human cartilage.
  • The blend of three polymers provides enough flexibility and durability to mimic the knee.
  • The next step is to test this hydrogel in sheep; human use can take at least three years.
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Predicting PTSD symptoms becomes possible with a new test

An algorithm may allow doctors to assess PTSD candidates for early intervention after traumatic ER visits.

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