The Checkup: What minimally conscious brains can do
This week I’ve been thinking about consciousness. What is the brain doing when we are unconscious? Is there a way to regain consciousness in someone who has lost it? You can read more about the mysteries and secrets of the mind in our Matter issue from last year. )
I’d come across a new study suggesting that people in a minimally conscious state can learn a rudimentary form of language, or at least a string of previously unknown syllables.It sounded fascinating, so I called up John Whyte, who has spent much of his career studying disorders of consciousness. Whyte is the ideal person to talk to about this kind of thing. He has so many mind-blowing insight and anecdotes.
He told me right at the beginning of our call that the brains of minimally aware people behave in many ways similar to conscious people, despite not being able to communicate or be aware of their surroundings. He also told me about some fascinating–and tear-jerking–attempts to pull people in this state back into consciousness. These will be covered in a moment.
This kind of research can be difficult to do in people who are not fully conscious or in an unresponsive wakefulness state (previously known as a vegetative .). These are distinct from being in a state of coma. People who are minimally conscious show intermittent flickers of awareness and communicate, but not consistently. People in a nonresponsive state of wakefulness can’t communicate.
People in either state experience periods between sleep and waking while those in a non-conscious state are unable to wake up.
Amazing brains
In the study I saw, Nai Ding from Zhejiang university in Hangzhou, China used a cap of electrodes in order to record brain activity in people who were not fully conscious. His team played audio of familiar words and the brain activity showed waves for both whole words and individual syllables. This suggests that they were recognizing each word.
But when the team played new words, the patterns in activity suggested that they were only processing the individual syllables. To “teach” participants the words, Ding played the new words over and again, many times. the participants showed brain activity for the entire words by the end of the experiment. This was similar to what they saw with . familiar words. This suggests that they had learned the new words.
“They are not even conscious, but they preserve some ability to learn”
Nai Ding of Zhejiang University in Hangzhou, China
“They still have the potential to learn words in a new language,” Ding told me. “I think that’s amazing… they aren’t even conscious, but retain some… ability learn.” Ding said to me that they still have the potential to learn words in a new language. Their brains have been able to form new associations.
This is not the first time that people with minimal consciousness or unresponsive wakefulness have shown some ability to learn. Others have demonstrated, for instance, that people who are minimally conscious can associate a beeping sound and air being puffed into the eyes. They will then blink when they hear the sound alone. What does this tell us about our brains? It shows how amazing our brains can be. It also shows how difficult it can be to understand consciousness and how it works. These neuroscientists are trying to find ways to help those who aren’t fully conscious. Ding hopes that his word-learning technique will encourage people to be more “plastic” and create new connections that may help them recover. But we don’t know if this ability to learn makes recovery easier or is more beneficial.
Bringing people back
Only a small fraction of the hundreds of thousands of people suffering from disorders of consciousness will ever recover. The exact number depends on the reason they lost consciousness. Only a fraction of them will recover. The less likely a person is to recover, the longer they remain unconscious. Multiple research groups are working together to find ways to bring people back to consciousness.
Some of these attempts involve inserting electrodes deep into the brain to reach a structure called the thalamus. This structure is thought to be part of the brain’s “seat of consciousness.” Zapping the brain in this way has helped to rouse a small number of people in the past.
Even drugs can work, albeit temporarily, for a small proportion of people. Whyte, now semi-retired, is a neuroscientist at Elkins Park’s Moss Rehabilitation Research Institute. He told me about his research on amantadine. Although the drug is intended to treat Parkinson’s disease (PD), some neurologists have tried it in patients who are not fully conscious.
When Whyte and his colleagues trialed it in 184 people in a minimally conscious or unresponsive (vegetative) state, they found that the drug could help speed up recovery–those taking the drug were faster to show signs of improvement, such as being able to respond to questions or use objects.
Another drug, zolpidem, appears to rapidly rouse a small fraction of cases, says Whyte. He recalls a young man who sustained a head injury while returning from summer vacation. The man was unconscious for three years. Within an hour, the drug made him conscious. He even waved and hugged both his parents.
Devastatingly, the improvements only lasted a few hours. When he spoke of the drug’s gradual decline in effectiveness, Whyte was in tears. The family decided to keep the drug in reserve for special occasions, so that their son could be woken by his grandmother. These cases provide a fascinating and heartbreaking insight into the complex and fragile nature human consciousness and the potential for technologies to help us understand and restore it. To find out more about some of these attempts, you can check out the following stories from Tech Review’s archive:
- In The hunt for hidden signs of consciousness in unreachable patients, Russ Juskalian meets neuroscientists looking for hints of consciousness in people who are entirely unresponsive.
- Raising consciousness, by Emily Singer, describes technologies revealing that the brains of people in a minimally conscious state respond to stories in a similar way to healthy brains, and that they can use their thoughts to communicate to some degree.
- And in a piece from last year, Lisa Feldman Barrett explores how your brain makes your mind.
Solving the organ shortage problem
Last week saw the millionth organ transplant performed in the US, according to the United Network for Organ Sharing. The first organ ever to be transplanted was the kidney, back in the 1950s. But organ donation really took off in the decades that followed–more than half of all organ transplants in the US have been performed since 2007, and 41,000 were performed last year alone, according to the organization.
It sounds like a lot but it’s actually very little. Over 100,000 people in the US are on the national transplant waiting list, and 17 people die every day waiting for a transplant.
Research teams and biotech companies are developing new technologies to address the problem. Lygenesis, for example, is about to start a trial that will involve growing multiple new mini livers inside people’s bodies. Renewal Bio is attempting to grow organs for transplantation in synthetic embryos. Others are looking for ways to save damaged organs in the hopes of either decreasing the need for organ donation or making more organs available for transplantation. Researchers at Yale have shown they can keep a pig’s brain cells working to some degree an hour after the animal has died. And the start of the year brought the explosive news that doctors had transplanted a gene-edited pig heart into a person for the first time. (The recipient, David Bennett Sr., died two months after the operation, and my colleague Antonio Regalado reported that the organ was infected with a pig virus. )
From around the web
- People across the Northern Hemisphere are gearing up for flu season, and it’s difficult to predict just how hard it will hit.
– Flu has bounced back in the Southern Hemisphere, which doesn’t bode well for those of us in the North (The Atlantic $)
– But getting your flu shot as soon as possible, alongside a covid booster, may not be in your best interest (STAT) - I don’t think I know anybody who hasn’t had covid by now. Some people seem to have escaped the infection. Scientists are still trying to figure out how they are protected. (Wired $)
- Thousands of women claim that talc in Johnson & Johnson’s baby powder gave them cancer. Although not all legal cases have been won, the company has made huge payouts in those that have. This lengthy article explains the company’s history and its new strategy to avoid any financial compensation. (New Yorker $)
- Poorer countries are missing out on vaccines and treatments for monkeypox. You would have thought we’d know more about the importance of equitable access for vaccines by now. (NYT $)
- Given that millions of people have long covid– at least 17 million in the European region alone, according to the latest figures from the World Health Organization– it’s vital we get to grips with one of the most debilitating symptoms: brain fog. (The Atlantic $)
That’s it for this week. Thank you for reading this far.
Jess
Correction: The drug that roused the young man in John Whyte’s care was zolpidem, not amantadine
I’m a journalist who specializes in investigative reporting and writing. I have written for the New York Times and other publications.
