<p>Thiashya is back answering another big question in science. This time, she explains whether our brains create consciousness.</p>
Your brain doesn’t care who you are. Your brain probably doesn’t even know you exist. So how does consciousness arise from the aggregate of trillions of cells, none of which (we think) are conscious?
I’m no expert in psychology, philosophy, neuroscience or any other field for that matter. One, two or thirty Google searches later and I’m still no expert. It’s a real big banger of a question. It is ‘the hard problem’. Do our brains create consciousness? How do we have consciousness? First of all, what is consciousness? We only ever have access to one consciousness – our own. We canonly see the physiological and behavioural correlates of others’ consciousness – attention, self-awareness, comprehension and so on. All consciousness that is not our own is inferred from behaviour. We consider other people as conscious only because they seem conscious. Consciousness is an immaterial thing, so we cannot observe it. Because it is an inherently subjective experience, it’s impossible to define it with third person objectivity.
Our perception of colours and sensations differ vastly when fronted with the same stimuli. Take for example the dress which confounded the internet last year – was it blue and black, or white and gold? Studies have stressed the importance of ‘cortical integration’ in maintaining consciousness – processing and combining multiple stimuli and senses to create an experience. Your experience of chocolate is the combination of sight, smell, taste, touch and past experience. But a computing machine has the same capabilities, constructing, storing and processing information the way our brains do. So what’s the difference?
Awareness is the difference – the ability to ascribe meaning to the interaction of many inputs. When you look out into the sky, your brain does not merely register, ‘that is blue’ like a wavelength detector. You are aware that it is blue. Does your brain produce that feeling of awareness? When we lose consciousness, we lose our comprehension of reality. Researchers propose that our consciousness is a result of a delicate balance of neural connectivity: too much or too little and consciousness slips away.
Enzo Tagliazucchi, a German physicist, recorded data from participants during states of wakefulness, ongoing sedation, unconsciousness and recovery. He and his colleagues used an anaesthetic drug to induce unconsciousness in participants whilst they were in a functional MRI. The results showed that brain activity varies widely between unconscious and conscious states. During wakeful consciousness, participants’ brains showed the activation of many overlapping and integrated networks to create a ‘stream of consciousness’. When the propofol kicked in, their brain networks showed a significant reduction in connectivity and variability – it was using the same pathways over and over again. This monotonous pattern of activity during unconscious states could be why it’s so difficult to wake people from comas.
It’s like mapping a city. If you were to repetitively take only one route from point A to B, you’d have no clue what was going on. But by thoroughly exploring all parts of the city; the highways, byways, alleyways – you get a pretty good overall picture. Their results suggest that there is an optimal point of connectivity to generate a meaningful construct of reality.
Our brains construct a model of the world we experience and at some point, we gain awareness. Michael Graziano, a Princeton University professor of neuroscience, writes that most of the consciousness discourse is concerned with how a magical internal experience arises from, or is produced by, our neurons. These are questions that don’t lend themselves to science very well, if at all. Instead, Graziano asks ‘How, and why, does a brain attribute subjective experience to itself?’
In order to understand this complex phenomenon, there are two routes we need to acknowledge. Firstly, we must understand how consciousness arises from neurons and secondly, how consciousness feeds back to our brains to produce awareness. Graziano writes: ‘the most basic, measurable, quantifiable truth about consciousness is simply this: we humans can say we have it’. Consciousness must impact our neurons so that we are able to recognise and contemplate it.
Very few theories are able to explain this. The most prevalent assumption in scientific literature is the idea that consciousness is an emergent property of the brain. It’s an ethereal, abstract feeling of sorts. It’s puzzling – we don’t know how this feeling arises or how it alters your neurons so that you are able to say that you have it.
Graziano’s attention schema theory does both. When you’re holding an object. Your brain is focusing its resources on the object. That’s attention.
So now you have a computation model with a large amount of information about the agent and the object. The model also contains information about the relationship between the two: your awareness. We can think about attention being a sort of data-handling method and awareness as being the brain’s means of keeping track of what it’s doing. Our brains insist we have subjective experience, because when it sifts through its data, it finds information pertaining to our being conscious. The heart of the attention-schema theory is that awareness is a model of attention and that computation errors can produce a strange, altered perception of reality – for example, the man who was insistent that there was a squirrel in his head.
Consciousness can be a bleak topic. Why are we conscious at all? Some philosophers suggest it has no function at all but to make us feel better about ourselves. But the awareness-schema theory suggests that consciousness evolved because it had a practical benefit. By attributing awareness to ourselves, we control our own behaviour – and by attributing awareness to the others, we developed incredible social intelligence.
It’s complex territory, that’s for sure. The idea that consciousness emerges somehow from the vast depths of our neuronal mish-mash is lacking and the attention-schema theory does fill in a lot of gaps.
Dan Dennet, an American philosopher, says consciousness is a little like magic. By real magic, people mean miracles and supernatural powers, not magic tricks. But the magic that can be done isn’t ‘real magic’. And when the magician tries to explain their tricks, people often prefer not to spoil the mystery of it. Perhaps we prefer to revel in the mystery of our consciousness conundrum. Perhaps this hard problem is best left unsolved.