Being You: A New Science of Consciousness

by Anil Seth

Under general anaesthesia, things are different. I could have been under for five minutes, five hours, five years – or even fifty. And ‘under’ doesn’t quite express it. I was simply not there, a premonition of the total oblivion of death, and, in its absence of anything, a strangely comforting one.

Maybe you will, if consciousness depends only on functional capacity, on the power and complexity of the brain’s circuitry, but maybe you won’t, if consciousness depends on a specific biological material – neurons, for example.

The essence of selfhood is neither a rational mind nor an immaterial soul. It is a deeply embodied biological process, a process that underpins the simple feeling of being alive that is the basis for all our experiences of self, indeed for any conscious experience at all. Being you is literally about your body.

our conscious experiences of the world and the self are forms of brain-based prediction – ‘controlled hallucinations’ – that arise with, through, and because of our living bodies.

It is undeniable that some organisms are subjects of experience. But the question of how it is that these systems are subjects of experience is perplexing. Why is it that when our cognitive systems engage in visual and auditory information-processing, we have visual or auditory experience: the quality of deep blue, the sensation of middle C? How can we explain why there is something it is like to entertain a mental image, or to experience an emotion? It is widely agreed that experience arises from a physical basis, but we have no good explanation of why and how it so arises. Why should physical processing give rise to a rich inner life at all? It seems objectively unreasonable that it should, and yet it does.

(A ‘mechanism’ – to be clear – can be defined as a system of causally interacting parts that produce effects.)

physicalism. This is the idea that the universe is made of physical stuff, and that conscious states are either identical to, or somehow emerge from, particular arrangements of this physical stuff.

idealism.

Sitting awkwardly in the middle, dualists like Descartes believe that consciousness (mind) and physical matter are separate substances or modes of existence, raising the tricky problem of how they ever interact.

Functionalism is the idea that consciousness does not depend on what a system is made of (its physical constitution), but only on what

the system does, on the functions it performs, on how it transforms inputs into outputs. The intuition driving functionalism is that mind and consciousness are forms of information processing which can be implemented by brains, but for which biological brains are not strictly necessary.

for functionalists, simulation means instantiation – it means coming into being, in reality.

Panpsychism is the idea that consciousness is a fundamental property of the universe, alongside other fundamental properties such as mass/energy and charge; that it is present to some degree

everywhere and in everything.

This is why I tend towards a functionally agnostic flavour of physicalism. To me, this is the most pragmatic and productive mindset to adopt when pursuing a science of consciousness. It is also, as far as I am concerned, the most intellectually honest.

According to the real problem, the primary

goals of consciousness science are to explain, predict, and control the phenomenological properties of conscious experience.

There is one more ‘ism’ which deserves mention, though it is a more informal ‘ism’ than those discussed in the main text. Illusionism is the view that (phenomenal) consciousness is an introspective illusion – that when we introspect about conscious states we misrepresent them as having phenomenal properties – qualia – that in fact they do not have. On one reading, which I disagree with, illusionism says that conscious states do not really exist. On another, which I am more sympathetic to, illusionism says that conscious experiences exist but are not what we think they are. It is possible, though not clear, that this reading of illusionism is compatible with what I will say in this book. For more on illusionism see Frankish (2017).

‘neurophenomenology’

Some experiments have made valiant attempts to distinguish conscious perception from attention, and from behavioural report. The results from so-called ‘no report’ paradigms, in which volunteers do not make behavioural reports about what they perceive, are particularly intriguing. In many of these studies, the remaining NCC does not include the frontal brain regions

We can

think of the real problem as exhaustively addressing comparative explanatory gaps in order to resolve, and perhaps dissolve, the absolute explanatory gap.

The adult human brain contains an estimated 86 billion neurons, and about a thousandfold more connections.

Functional MRI (fMRI) measures a metabolic signal (blood oxygenation) related to neural activity – it offers high spatial detail but is only indirectly related to what neurons do. EEG measures the tiny electrical signals generated by the activity of large populations of neurons near the cortical surface. This method tracks brain activity more directly

than fMRI, but with lower spatial specificity.

In thermodynamics, temperature is a large-scale property of the movement of the molecules within a substance; specifically, the mean molecular kinetic energy. Faster movement, higher temperature. ‘Heat’ becomes the energy transferred between two systems at different temperatures.

Consciousness instead seems to depend on how different parts of the brain speak to each other. And not the brain as a whole: the activity patterns that matter seem to be those within the thalamocortical system – the combination of the cerebral cortex and the thalamus (a set of oval-shaped brain structures – ‘nuclei’ – sitting just below, and intricately connected with, the cortex).

But for the most part, the huge disturbance in brain activity caused by TMS does not generate any alteration in conscious experience at all. Maybe this is not so surprising. It just shows we are not aware of what our neurons are doing – and why should we be?

perturbational complexity index,

They found that PCI magnitudes correlated

extremely well with levels of impairment, as independently diagnosed by neurologists.

We also found that complexity during rapid eye movement (REM) sleep is much the same as during normal conscious wakefulness, which makes sense because REM sleep is when dreaming is most likely – and dreams are conscious.

a patient who had been admitted with a diagnosis of vegetative state was able to answer yes/no questions by imagining playing tennis for ‘yes’ and imagining walking around their house for ‘no’. A laborious way of communicating, for sure, but a life-changing development for those with no other way to make themselves understood.

question is whether consciousness is ‘all or none’ – either the lights are on or they aren’t – or whether it is ‘graded’, with no bright line between consciousness and its absence.

This question applies equally to emergence of consciousness in evolution or in development, as to when returning from the oblivion of anaesthesia or dreamless sleep.

At the level of neurochemistry, the classic psychedelics – LSD, psilocybin, mescaline, and dimethyltryptamine (DMT, the active ingredient in the South American hallucinogenic brew called ayahuasca) – work primarily by affecting the brain’s serotonin system. Serotonin is one of the brain’s primary neurotransmitters – chemicals which wash through the brain’s circuits and which influence how neurons communicate. Psychedelic drugs influence the serotonin system by binding strongly to a specific serotonin receptor, the 5-HT2a receptor, which is found throughout much of the brain. One of the main challenges for psychedelic research is to understand how these low-level pharmacological interventions alter global patterns of brain activity, so as to deliver profound changes in conscious experience.

Robin’s team had previously discovered that the psychedelic state involves striking

alterations in brain dynamics, when compared to a placebo control condition. Networks of brain regions that are usually co-ordinated in their activity – so-called ‘resting-state networks’ – become uncoupled, and other regi...

Overall, the picture is of a breakdown in the patterns of connectivity that characterise the brain under normal conditions. Robin’s idea was that these breakdowns could account for signature features of the psychedelic state, like the dissolution of bou...

The results were clear and surprising: psilocybin, LSD, and ketamine all led to increases when compared to a placebo control. This was the first time anyone had seen an increase in a measure of conscious level, relative to a baseline of waking

rest.

brain activity in the psychedelic state becomes more random over time, in line with the freewheeling reorganisation of perceptual experience that people frequently report during a trip.

Conscious experiences are informative because every

conscious experience is different from every other conscious experience that you have ever had, ever will have, or ever could have.

Looking past the desk in front of me through the window beyond, I have never before experienced precisely this configuration of coffee cups, computer monitors, and clouds – an experience that is even more distinctive when combined with all the other perceptions, emotions, and thoughts that are simultaneously present in the background of my inner universe. At any one time we have precisely one conscious experience out of vastly many possible conscious experiences. Every conscious experience therefore delivers a massive reduction of uncertainty, since this experience is...

Redness is redness because of all the things it isn’t, and the same goes for all

other conscious experiences.

‘integrated’

every conscious experience appears as a unified scene.

We do not experience colours separately from their shapes, nor objects independen...