Covert Consciousness is a New Kind of Coma
When patients appear to be unresponsive in a coma or vegetative state but are actually conscious
Hiya!
What happens in the mind of someone in a coma? It’s a mystery that’s confounded medical professionals and inspired creative fictional stories for decades. Though perhaps no one has wondered more than the loved ones of coma patients. Can they hear? Are they dreaming? Does it depend on the severity of the brain injury? And perhaps most importantly, how an we know?
Mostly, these questions remain unanswered, but with the help of technology and creative neuroscientists, experts are making some headway. Recently, scientists discovered that some patients that appear to be in comas may actually be conscious and even found a way to communicate with them.
Coma Categories
When someone is in a coma, it means they're in “a state of profound unconsciousness caused by disease, injury, or poison.” They do not awaken or respond to stimulations such as noise, light, or pain. They look like they are sleeping, except coma patients don’t experience the usual sleep-wake cycles.
Coma patients may all seem the same, but there are different levels and categories of comas. Experts use scales such as the Glasgow coma scale to assess a patient’s responses to various stimuli and estimate the patient’s level of consciousness.
Patients who are considered comatose are in particularly deep coma states. Many can’t breathe independently, requiring ventilators and feeding tubes to keep them alive. Those who emerge from a comatose state usually need rehabilitation that can last weeks to months.
However, patients in a vegetative state don’t usually require life support. These patients have or regain partial awareness. Some patients in vegetative states open their eyes and respond to some sensations, including pain. They may also cry or laugh spontaneously, track movements with their eyes, and even scream. However, these actions are more random than deliberate.
If a patient remains in a vegetative state for longer than a few weeks, they’re considered to be in a “persistent vegetative state.” At the year mark, the patient is classified as a “permanent vegetative state,” or “wakeful unconsciousness.”
Then you have people in minimally conscious states who are more active. These patients may provide non-verbal responses and intermittently follow commands, such as deliberately tracking objects with their eyes.
These classifications not only helped physicians identify a patient’s prognosis better but also better track their progress or decline. For instance, a patient who transitions into a minimally conscious state from a previously vegetative state has a greater chance of recovering.
Finding the distinctions between coma states is a big deal and will help countless people, but most of what’s known relies on external signals — how well the patient responds to stimulation from our shared reality. Meanwhile, very little is known about the internal conditions of the patient while they’re in a coma.
Covert Consciousness
Thanks to technology and the curiosity of neuroscientist Adrian M. Owen, now at Western University in Ontario, and his colleagues, a new state of coma consciousness has been discovered. In 2006, they published a paper in Science about a young woman believed to be in a vegetative state due to a severe traumatic brain injury.
The team used a functional magnetic resonance imaging (fMRI) machine to assess the blood flow in the patient’s brain, which illuminated which areas were active. During the scan, researchers asked her to imagine walking through the rooms of her house. Then they asked her to imagine playing tennis.
The brain patterns for imagining these tasks are distinct, so completing them would indicate that she was intentionally changing her thoughts. Amazingly, and much to Owen’s surprise, not only did the patient appear to follow Owen’s prompt, the scan showed that the patient’s brain was activating similarly to what they saw in healthy (non-vegetative) volunteers.
Since Owen’s paper, covert consciousness has been identified in patients worldwide experiencing various brain injuries and time frames. For instance, doctors at the intensive care unit at Massachusetts General Hospital found that even patients who were recently hurt can be in states of covert consciousness.
Diagnosis
Determining whether a patient is comatose or in a vegetative state uses tests that judge their physical responsiveness. Experts use a similar method to diagnose covert consciousness, except instead of observing the patient’s physical reactions, they observe their brain reactions.
The clinicians may ask a patient to imagine swimming or opening and closing their hands while the researchers observe their brain activity. In addition to fMRI machines, electroencephalography (EEG) machines — which record the electrical activity of your brain — are also useful for detecting covert consciousness.
Multiple research groups worldwide have reproduced Owen’s results while using different methodologies to analyze a patient’s brain activity. They find that patients experiencing covert consciousness can change their brain patterns to reflect the physical movement asked of them, but their physical body shows no indication of moving.
But How Do We Know?
The mere existence of covert consciousness is incredible and may help us better understand the mind and consciousness in general. But how do we really know whether someone is conscious and deliberately following the researcher’s prompts? Couldn’t the words themselves trigger the reaction? I mean, maybe it’s kinda like our mirror neurons, which are brain cells that respond the same whether we witness someone perform an action or perform it ourselves.
Well, Martin Monti, a cognitive psychologist at the University of California, Los Angeles, wanted to know too. So he tweaked the methodology used to detect covert consciousness to determine whether the patients could answer yes or no questions.
Like Owen, Monti asked his patients to imagine either walking through their home or playing tennis. Except he didn’t stop there. Monti asked the patients a series of yes or no questions and instructed the patients to intentionally think about playing tennis if their answer was “yes,” and to think about walking through their home if their response was “no.”
They found that “Of the 54 patients enrolled in the study, 5 were able to willfully modulate their brain activity.” However, they also state that only “[o]ne patient was able to use our technique to answer yes or no to questions during functional MRI.” So it seems the results of Monti’s study confirm that it is indeed possible to communicate with some patients who are in vegetative states. But it’s perhaps less widespread than initially thought.
Perspective Shift
We can thank advancements in technology for discovering covert consciousness at all, but there’s plenty of room for improvement. While the fMRI and EEG machines provide a peak into the brain's inner workings unlike never before, the technology is still limited. Though given the accelerated rate of tech, it might not be long before the kinks are ironed out.
In the meantime, neurologists and laboratories around the world are working to develop ways to better identify which patients are likely to be in a covert consciousness state prior to undergoing advanced testing with the EEG and fMRI machines. However, progress is slow because of our limited information about consciousness in general and how it works.
It would be helpful if the patients could give us a clue as to what comas are like, but similar to many recovering coma patients, none of the patients who have “woken up” from a state of covert consciousness and recovered the ability to communicate remembers their experience. So I guess we’ll just have to wait to learn more.
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