A greater scientific understanding of consciousness is allowing researchers to quantify exactly how conscious we are at any given moment, and the resulting measurements are providing new insight into the likelihood of coma patients to recover.
While consciousness has long been the subject of metaphysical debates, it is only recently that scientists are beginning to develop a picture of how it manifests in our brains.
One of the pioneers of this new field is Stanislas Dehaene, professor of experimental psychology at the Collège de France in Paris. He and his colleagues were the first to show that the cortex – the topmost brain region associated with high-level functions and thought – is activated by words that aren't consciously perceived.
Researchers have shown that a surprising amount happens in the brain without conscious awareness. Numerical values, meanings, grammatical information, and more, can all be processed non-consciously.
Over the course of a five-year project called NEUROCONSC, funded by the EU’s European Research Council (ERC), Prof. Dehaene and colleagues have been exploring the limits of this non-conscious processing and developing a theory of what consciousness is.
A phenomenon called masking is the most common technique used for studying consciousness. If a word is briefly flashed in front of someone's eyes, they can easily read it, but if it is immediately overlaid by a string of letters, they don't perceive it, and can't report what it was.
Researchers can vary the delay between the word and mask to find the threshold of conscious awareness, where the word is perceived half the time. Other techniques include binocular rivalry, where separate images are presented to each eye but participants are conscious of only one, and various methods of manipulating attention.
Using these techniques, Prof. Dehaene and colleagues found that when a participant becomes able to report, say, seeing a word, they can suddenly do a wide range of new things with the information, including naming and remembering it.
This seems to be because information is suddenly shared throughout the brain. When a participant becomes consciously aware of something, the initial neural response is amplified many-fold, and suddenly spreads, as synchronised activity, through a wide network of regions, including many parts of the cortex. Prof. Dehaene calls this the Global Neuronal Workspace.
Now, Prof. Dehaene and colleagues, including Dr Jacobo Sitt at the French Institute of Health and Medical Research (INSERM), have used this insight to develop ways of measuring consciousness. For instance, one measure involves quantifying the degree to which information is shared across distant brain regions.
They have shown that this measure can distinguish between electroencephalography (EEG) recordings of brain activity from patients who were conscious, in a vegetative state, or minimally conscious (where patients are occasionally able to respond to simple commands).
‘We found huge differences between patients that were in vegetative state - so unconscious - and patients that were in a minimally conscious state,’ said Dr Sitt. Patients with locked-in syndrome, who are fully aware but unable to communicate, register as conscious.
Now, under another ERC-funded project, the team have developed a system, called CoMonIn (Consciousness Monitoring Index) for automatically monitoring consciousness. This includes an offline mode, where EEG recordings are uploaded to a web server, and a real-time version, using a laptop and EEG head-set, which can be used by the bedside.
‘We're trying to explore almost philosophical phenomena, in terms of molecules in the brain.’
Dr Hagar Sagiv, Tel Aviv University, Israel
This version can deliver appropriate audio, video, or even electrical, stimulation when higher levels of consciousness are detected, to try to increase the chances of patients regaining consciousness.
Most recently, they have used machine-learning techniques and a database of EEG recordings to predict who goes on to recover from coma-like states, with around 77% accuracy. They are now looking for commercial partners to take their system to market.
Meanwhile, other researchers are studying altered states of consciousness through a natural long-lasting window that is available at the end of every day.
‘We are ignoring the fact that every night we go to sleep and become unconscious of our external environment,’ said Dr Hagar Sagiv from Tel Aviv University, Israel. ‘We see sleep as another lens through which to look at consciousness.’
Dr Sagiv is a researcher in the lab of Dr Yuval Nir, whose STATEDEPENDENTPROCES project has been funded by the EU. She is investigating exactly how the brain disconnects the senses during sleep by comparing the brain’s activity in wakefulness and REM sleep.
She is particularly interested in REM sleep because of its similarity to waking in terms of metabolism and activity. REM sleep is when we dream, so there are also experiences of a sort, but of course sleepers remain disconnected from external events.
There are reasons to suspect a neurotransmitter called noradrenaline may be involved, partly because the locus coeruleus (the part of the brainstem that produces noradrenaline), is inactive during sleep.
To test this, Dr Sagiv is conducting experiments where participants are given drugs that alter levels of noradrenaline in the brain during wakefulness, to see whether this is sufficient to mimic sleep and change their sensitivity to sensory input. Parallel studies are using cellular recordings in animals, together with a cutting-edge technique for communicating with neurons, called optogenetics, to reveal the underlying mechanisms.
While the project could have similar practical implications as other studies of consciousness, there is also a profound basic science aspect to studying consciousness at such basic biological levels.
‘What's special about this is we're trying to explore almost philosophical phenomena, in terms of molecules in the brain,’ said Dr Sagiv. ‘This is one of the biggest challenges we have as scientists, to understand the biological basis of consciousness - twenty years ago it was a question for philosophers, not scientists.’
Professor Martijn Nawijn, an immunologist at the University of Groningen in the Netherlands, tells Horizon about his quest to map every cell in a healthy human lung. He says this work should help to understand more about the causes of lung disease - which is comparatively understudied - and should lead to new therapies in the next 15 to 20 years.
There was one science story that dominated 2020 and coronavirus is likely to remain a dominant theme in 2021. But from vaccine rollout to lessons for future pandemics and – that other big challenge that we’re facing – climate change, how will the year in science play out? We asked a selection of our interviewees about lessons from 2020 and what needs to happen in their fields in the coming year.
Artificial intelligence (AI) used by governments and the corporate sector to detect and extinguish online extreme speech often misses important cultural nuance, but bringing in independent factcheckers as intermediaries could help step up the fight against online vitriol, according to Sahana Udupa, professor of media anthropology at Ludwig Maximilian University of Munich, Germany.
In the summer of 2014 a strange building began to take shape just outside MoMA PS1, a contemporary art centre in New York City. It looked like someone had started building an igloo and then got carried away, so that the ice-white bricks rose into huge towers. It was a captivating sight, but the truly impressive thing about this building was not so much its looks but the fact that it had been grown.
Independent factcheckers can bring context to AI tools, says media anthropologist.
Live mycelium networks, capable of information processing, could be used as building materials.
Dr Kate Rychert studies ocean plate structures.