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Can scientists solve the conundrum of consciousness?

Sometime in the late 1980s, two Oxford scientists examined PS, a patient who had suffered damage to the right side of her brain. The damage left her unable to notice things to her left. Even when she drew objects, she would draw their right sides perfectly but completely leave out the left. She didn’t even realise that the drawing was incomplete – it was like the left side of objects just didn’t exist for her.

The scientists then showed her pictures of two houses, with the left side of one of the houses on fire. PS could not see any difference between the two houses. When asked which house she would choose to live in, however, she pointed to the house that was not on fire – not just once, but almost every time. Her brain seemed to be processing information about the burning left side of the house; she just seemed unaware of it.

This inherent yet inexplicable awareness is a major part of a phenomenon that we all experience – consciousness.

“Consciousness is like … the feeling of being. The feeling of being present, of being aware of a thought, perception, sensation,” says Nithin Nagaraj, mathematician and Professor at the Consciousness Studies Programme at the National Institute of Advanced Studies (NIAS), Bangalore. We all inherently experience it, he adds, but it is very hard to define conceptually.

‘Consciousness is like … the feeling of being. The feeling of being present, of being aware of a thought, perception, sensation’

Being conscious is an experience that is intricately tied to all our lives, but we still struggle to wrap our heads around it. One possible definition for consciousness would be the feeling of “what it is like to be us” – the experience of existing inside our heads and being aware of everything around us. We are conscious of external sensations, along with our thoughts, our emotions, and our pain. We are conscious when we are awake, but dreams and hallucinations also feel like conscious experiences. It is like an immersive “inner movie” that runs in our minds and around us, where each of us is the main character.

But how exactly our brain generates this inner movie or “makes” us conscious has eluded scientists for decades, mainly because it is such an irrefutably “first-person” experience.

“The simple fact is, I know I’m conscious. I don’t know if you, or anybody else, is conscious,” points out SP Arun, Professor and Chair of the Center for Neuroscience (CNS) at IISc. “You sort of assume that everybody else is conscious as you’re interacting. [But] I can’t think of an objective way to test whether you are conscious.”

‘I can’t think of an objective way to test whether you are conscious’

Aditya Murthy, Professor at CNS, agrees; he thinks that objectively recording brain activity may not be enough to explain how a subjective, qualitative event seen from the inside arises.

Bridging these objective-subjective and third-person-first-person gaps has been the root of all problems in consciousness research.

But this hasn’t stopped scientists from trying. In the 1990s, prominent neuroscientist Christof Koch, now a Meritorious Investigator at the Allen Institute of Brain Sciences in Seattle, was young, enthusiastic, and highly confident in the advancements in brain-imaging and brain-recording techniques at the time.

 

 

In 1998, amidst a few jovial drinks in a bar in Germany, Christof famously struck a bet with philosopher David Chalmers. The wager was that in 25 years, scientists would have solved at least one major challenge: nailing down the “neural correlates of consciousness (NCCs)” – specific features of neurons that could explain any given conscious experience.

“How to construct a theory that tells us which physical systems are conscious … is one of the deepest, most fascinating problems in all of science,” writes computer scientist Scott Aaronson, Professor at the University of Texas at Austin, in his blog. “I don’t know of any philosophical reason why [it] should be inherently unsolvable … but humans seem nowhere close to solving it.”

Christof is, however, still keen on solving the consciousness problem. He challenged David to another “double-or-nothing” bet – by 2048 they should have a brain marker for consciousness.

Apart from the near certainty that both of them will be a bit too old for wine, what will happen in another 24 years is hard to say. As of now, the battle for the best theory of consciousness is ongoing – a battle that Christof himself was instrumental in starting more than 30 years ago.

One theory to rule them all

At first, neuroscientists just avoided the consciousness problem. For most of the 20th century, a subjective awareness of ourselves and the world around us seemed too vague a topic to be studied using science.

Then, in 1990, Francis Crick, known for his role in solving the mystery of DNA structure, decided to enter the fray. He co-wrote a paper with Christof titled “Towards a Neurobiological Theory of Consciousness”, which brought the much-avoided “C” word – something only philosophers and psychologists pondered about – back into the minds of neuroscientists. The paper claimed that the essence of consciousness has to lie within the circuitry of our brains; it was just a matter of finding these “neural correlates”.

The essence of consciousness has to lie within the circuitry of our brains; it was just a matter of finding these “neural correlates”

Spurred, scientists around the world began examining different regions or neural signatures in the brain that could be linked to consciousness. Others tried to unify scientific observations into elegant theories that could neatly explain our subjective sense of being.

One such theory, championed by cognitive scientist Stanislas Dahaene at the Collège de France in Paris, is the global workspace theory (GWT).

According to GWT, our brains end up receiving all kinds of information, but only some information passes through a “bottleneck” to reach a “global workspace”. This is how we become “conscious” of some information, which is then integrated and broadcast to other parts of the brain for further decision-making. Based on brain-imaging studies, this process most likely occurs within a network of neurons in the front of the brain – a region called the prefrontal cortex (but it also includes other parts of the brain).

Christof, however, was not convinced. He teamed up with neuroscientist Giulio Tononi at the University of Wisconsin-Madison, who proposed a competing theory called Integrated Information Theory (IIT). Giulio believed that consciousness is an intrinsic property that arises from a network that has a “cause-and-effect” power – the network can change its own state in some way (cause) and it can also affect its future states (effect). The neural structure that best fits this description, according to IIT theorists, is a grid-like arrangement of neurons somewhere in the posterior cortex, or the back of the brain – a region they called the “hot zone”.

These two leading theories of consciousness went head-to-head in an “adversarial collaboration”, in which scientists worked together, designed different experiments, and tested predictions about consciousness to see which theory fits better.

But when the results were unveiled last year, no clear winner emerged. Neither theory was a perfect fit.

Even before the highly publicised contest, scientists had started picking out flaws in both theories. For example, people with epilepsy have had surgery to remove portions from the front of their brain, yet they seem perfectly conscious – countering the predictions of GWT. And IIT, in its simplest sense, suggests that any system with the right wiring to integrate information can potentially be somewhat conscious. This implies that to some extent, however small, even our phones and laptops could have inner senses of being – a philosophical idea called panpsychism that has some scientists shaking their heads in sheer disbelief.

Besides these two theories on consciousness, there are at least twenty others, ranging from “higher-order” theories to quantum mechanics being at the core of consciousness.

All these theories describe how consciousness could work, but there is still no clear, convincing answer to how it actually does.

“It’s a bit frustrating,” says Aditya. “I mean, we’re not able to get something that’s so obvious to all of us internally. We can record every activity of 100 billion neurons, but unless we understand how this activity enables experience, we risk missing, I think, the essence of what makes us human.”

Consciousness in the brain
Apart from the front and back of the brain, other regions of the brain have been implicated in different conscious experiences.
1.Claustrum: A 2014 case study showed that electrically stimulating this sheet-like structure below the cortex caused a woman to stare ahead blankly, looking almost unconscious. But another patient who had his claustrum destroyed by encephalitis turned out to be perfectly conscious.
2.Anterior insula: Nestled deep within the brain, this region has been found to play a role in multiple subjective experiences, mostly by integrating our internal states and emotions with external sensations. It is a strong candidate for being the seat of “sentience”, a place in our brain which regulates our sense of self.
3. Thalamus: In some comatose patients, stimulating the thalamus – a major hub that is connected to multiple parts of the brain – using ultrasound has been correlated with them recovering from the coma.

Components of consciousness

Anil Seth, a cognitive neuroscientist at the University of Sussex, suggests another approach in his Aeon essay – instead of trying to solve the consciousness problem head-on, we could break it down and address different aspects. He draws a comparison with the study of life – at one time scientists baulked at the idea of simple biochemistry being behind complex processes that keep us alive. But over time, they accepted it and started to think about life in terms of its various functions, like reproduction, growth, and metabolism. We may still not know how exactly biochemical processes give rise to living systems, but chipping away at the parts that make up life has helped us learn more about it.

In 2023, a NeuroConsciousness initiative was started at IISc, with support from KR Sreenivasan, Dean Emeritus of the NYU Tandon School of Engineering and an alumnus of IISc. As part of the initiative, several labs at CNS are studying the neural basis of different features that ostensibly make up our inner being.

Aditya’s lab, for example, probes questions about our sense of self – an aspect of consciousness that, in Anil’s words, “we cling to most tightly.” They are looking at how our brain connects with our sense of agency, and how that helps us think or introspect about our decisions and predict the consequences of our movements.

“For example, when you move your eyes voluntarily, you know that stuff in the world will move on your retina. But as your brain is monitoring your eye movements – you can infer that the movement on the retina is caused by your own action, and not by an external movement,” says Aditya. “In other words, you can distinguish the stuff that’s changing out there versus the stuff that’s changing as a consequence of what you are doing. In principle, such a computation may be the kernel of agency.”

There’s a theory that patients with disorders of agency, like schizophrenia, are not able to distinguish their inner world from external changes. They start hearing voices in their head, but to them, they appear as hallucinations of external people directing them to act.

“This concept of agency is linked very strongly to our will to act on things. The idea that you are an agent itself is quite profound, right? That you have control over your actions,” says Aditya. “So that might be the first shell of basic consciousness – you are aware of your body and aware that you can actually control parts of your body.”

‘This concept of agency is linked very strongly to our will to act on things… that might be the first shell of basic consciousness’

A planned movement
Scientists suggest that when the brain plans a movement, a motor command goes down to the muscles, but a part of that command also goes back into the brain in the form of an “efference copy”. The brain can actually use this to anticipate the sensory consequences of the action, something that other researchers have also shown in the case of eye movements. They found that after an action, a signal from the muscle goes back into the brain and correlates with participants moving their eyes accordingly – thus tracking the effects of their own movement. Aditya and his team intend to use the idea of motor efference to test its role in agency, in humans.

Arun, also part of the initiative, is trying to understand another aspect of consciousness: visual perception. He studies how the brain transforms objects we see into things we perceive.

“In a certain general sense, whatever you see is already there in the image that comes into your eyes, right? But then the brain is spending almost 50% of its real estate to actually process the image, to figure out what is there,” explains Arun. “So, the brain is converting the information present in the image into some complex format. A lot of our research is aimed at understanding that format.”

“The way I see it, perception, decision making, attention – all of these are basic building blocks of cognition, and in a way, consciousness,” he adds.

Perplexed by mirrors
Sometimes the brain gets confused by its own processing, like in the case of mirror images. One of Arun’s lab’s projects is understanding why young children get confused by alphabets that mirror each other and end up innocently interchanging their b’s and d’s.
“That’s a confusion that doesn’t come from the image itself, it’s a processing feature of your brain,” says Arun.
Our brain learns (either during childhood or through evolution) that two images that mirror each other are really the same object, seen from different viewpoints. Young children learning to write English initially get confused because of this adaptive learning; they think alphabets that mirror each other are the same. It is something we unlearn as we grow older and read more.
According to Arun, adult humans also tend to get confused while processing mirror images, especially if they are mirrored along the vertical access (left-right mirroring). We do better with horizontal axis (top-bottom) mirroring. But monkeys process mirror images quite differently, getting equally confused with both kinds of mirror images. Arun’s group is trying to understand the neural basis of this difference.

Supratim Ray, Professor, CNS who is also part of the initiative, is particularly interested in the meditative state – a slightly altered state of heightened consciousness that some people achieve through practice.

“The fact that over thousands of years, so many traditions have been developed to control your mind and not let it wander, and be in a state where you are calmer, is a great neuroscience question in its own right,” says Supratim.

He is keen on seeing what happens in the brain during meditation, specifically looking at gamma waves – a kind of brain wave generated when neurons fire in synchrony at around 40Hz. Gamma waves are known to be modulated by high-level cognitive behaviours, like paying attention to a particular task. These waves were an early contender for driving consciousness as well, until people found them even in unconscious, anaesthetised animals.

“We [want to] learn about the brain and the effect of meditation on the brain. Meditative practices could have a neuroprotective role potentially, and those are all beneficial things, as neuroscientists for us to study,” Supratim says.

Studying different aspects of consciousness can also help untangle our complex web of emotions and teach more about phobias and psychiatric disorders. Conflicts between conscious and unconscious pathways in our brain could be leading to conditions like anxiety and depression, scientists think. We might even learn how to treat patients in a coma, or patients with brain injuries who slip into a “wakeful unawareness” – where they seem to be awake but unable to respond to stimuli. Such patients in a vegetative state may even be conscious, but with their ability to respond completely destroyed – figuring out their level of consciousness can help us know if they are ‘still them’ inside, to some extent.

Can artificial intelligence (AI) ever become conscious?
Some scientists are concerned AI could become sentient in the future, or may already be exhibiting signs of conscious intelligence. But others feel we don’t need to worry yet.
No matter how good AI gets at processing, says Nithin, it cannot yet “understand” the way we do. “If you tell an AI a joke, it won’t laugh. It’s just processing,” he says. “Understanding is a conscious experience.”
Aditya believes AI can not really evolve consciousness unless it develops the way humans and other animals do, and having agency of its own body (if it were to have it), might be necessary first.
Instead of consciousness, Arun thinks we should be asking whether AI can have the same kind of cognition we do. According to him, the answer is no. Not yet, at least. “There’s no danger that AI is suddenly becoming more intelligent than humans because currently, they just don’t see, they don’t understand speech, and they can’t interact in the world the way we do,” he adds. “It’s like asking if calculators will take over the world!”
Scientists are debating whether large language models (like the ones driving ChatGPT) have some form of understanding – even if it is not human. Broadening the definition of what “intelligence” could mean for machines, scientists think, could help us better understand diverse forms of cognition.

But many aspects of consciousness remain shrouded in mystery. As David explains in his 2014 TED talk, questions like “how do we decide when to move” and “how we perceive objects” are immensely valuable and interesting, but still come under the “easy” problems of consciousness. Given enough time and money, experts will eventually get to them.

A few years before his bet with Christof, in a 1994 conference in Arizona, he became famous for outlining the “Hard Problem of consciousness”. And that is: Even as we sense, perceive, and respond to stimuli, why do these different processes in the brain actually lead to us feeling and experiencing things? And how does our brain manage to generate this ineffable feeling of experience inside of us? Talking to journalist Oliver Burkeman at The Guardian, he invokes the logical possibility of a philosophical zombie with no conscious feelings or experiences. Not the snarling, flesh-eating kind, but a “creature” that looks and behaves exactly the way we do – except it is completely empty inside. Evolution could have resulted in such robot-like creatures, but it didn’t; it resulted in us. And not only are we conscious of the world, but we are also conscious of ourselves, sometimes to a fault.

Even if we do study different aspects of consciousness, solving the “hard problem” scientifically seems nearly impossible. So, some researchers are wondering if science alone will help us understand it.

Some researchers are wondering if science alone will help us understand the “hard problem” of consciousness

Beyond the brain

Apart from neuroscientific studies, Sreenivasan sees value in exploring the diverse views of consciousness via IISc’s NeuroConsciousness initiative. The initiative also organises an annual workshop, to foster discussions between various consciousness experts who may have differing views.

Some of these views include the ancient Upanishadic and Buddhist traditions, such as consciousness being a fundamental entity like space or time.

A scenario to think about this, according to Nithin, would be to imagine consciousness to be this all-encompassing entity, and that our brains just transmit this feeling of being – they don’t create it.

“Think of the brain as a trans-receiver,” says Nithin. “Let’s say I have a radio, right? There is a base station that is transmitting the song, but I cannot listen to the song unless I am tuned to the song. The radio is required, but the radio does not generate the song.”

To many scientists, the idea that consciousness can exist beyond the brain seems impossible to test rigorously with current scientific methods. But some scientists, psychologists, and physicians think lucid near-death experiences (NDEs) are a form of evidence. These are conscious, other-worldly, out-of-body experiences that have been reported by some cardiac patients who had flatlined and then been resuscitated. If one can have a conscious experience when there is no blood flow to the brain, the scientists say, then perhaps consciousness can linger on, even without the buzz of neurons.

To many scientists, the idea that consciousness can exist beyond the brain seems impossible to test rigorously with current scientific methods

But other scientists are pushing back, saying that the brain doesn’t die immediately after the heart stops; it is a slow process and not a sudden switch-off. According to them, NDEs are usually accompanied by huge surges of brain activity – indicating that any conscious experiences that accompany them must be caused by the brain. They theorise that it is a desperate survival tactic, the brain’s last-ditch attempt to revive itself before dying.

“One view is that [consciousness] is an emergent phenomenon that can be explained by understanding the complexity of the human system, particularly the brain. And the other is that it is an irreducible entity,” says Sreenivasan. “I don’t know where the truth lies, and I thought that something that will attempt to understand each of these two views in relation to the other would be very helpful.”

A central mystery of life

“Some problems in science are so hard, we don’t really know what meaningful questions to ask about them – or whether they are even truly solvable by science,” wonders science writer Philip Ball in Quanta.

For now, scientists are sticking to chipping away at the aspects of consciousness that seem most penetrable by science – the “easier” problems – even as other aspects continue to fuel countless scientific, philosophical, psychological, and even spiritual debates.

For now, scientists are sticking to chipping away at the aspects of consciousness that seem most penetrable by science

“We are hoping, because of the initiative that we have taken on, that we can educate the public about the difficulty of the problem,” says Arun.

There is a distinct possibility that scientists may never fully crack the code of consciousness. But there is a silver lining. Amidst all the intense discourse and intriguing uncertainty, we get to learn a lot about the brain and ourselves. “This sparring has a lot of value,” says Supratim. “I think this is what keeps up the intellectual rigour and, in some ways, it shouldn’t die out.”

He jokingly asks what we will do if we have an answer to consciousness. “Then, you know, there’s nothing else to do!”