Tracking the footprints of consciousness

The Feeling of Life Itself, by Christof Koch, is out now, published by The MIT Press. We asked him some big questions.

What is consciousness?
Somebody is conscious if, in the words of the philosopher Thomas Nagel, there is ‘something that it is like to be’ in that state, such as experiencing the delectable taste of Nutella, the sharp sting of an infected tooth, the slow passage of time when bored, or the sense of vitality and anxiety just before a competitive event. Reflecting on one’s own consciousness is a category of conscious experiences unique to adults, not developed in infants and children and not present anymore in patients suffering from dementia and other neurological ailments.

Consciousness is fundamentally about being, not about doing. As a consequence, I can never directly experience the conscious feelings of someone else, but can only infer these from their behavior, including what they tell me (assuming they can speak).

Are animals conscious?
All the behaviors and states associated with human consciousness have their precursors in non-human animals, including episodic memory, symbolic communication, courtship rituals, emotions, decision making, imitation learning, counting, food caching, tool making, recognition of self and on and on. Furthermore, consciousness is far more elementary than just having abstract thoughts. There is little refined, reflective or abstract about an itchy nose, a throbbing toothache, the smell of rotten cheese, or a full belly. The majority of biologists and those of us who have dogs and cats have no doubt that most, if not all animals, experience the sounds, sights and smells of life.

Charles Darwin, in his last book, published in 1881, wanted ‘to learn how far the worms acted consciously and how much mental power they displayed’. Studying their feeding behaviors, Darwin concluded that there was no absolute threshold between complex and simple animals that assigned higher mental powers to one but not to the other. No one has discovered a Rubicon that separates animals that have experiences from those that are pure zombies, without any feelings.

Again, I can never directly experience the way dogs experience the world, redolent in odors. I can just infer, from evolutionary continuity, from the fact that our genomes and our brains are so similar, that they too have subjective experiences.

Where does experience hide?
More than a quarter of a century ago, Nobel Laureate Francis Crick and I defined the neuronal correlates of consciousness as the minimal neuronal mechanisms jointly sufficient for any one conscious percept. These are the brain regions and assemblies of active neurons that are the physical substrate of any one subjective experience.

Powered by advanced instrumentation, neuroscientists are tracking the footprints of consciousness within its principle organ, the nervous system. Surprisingly, many brain regions do not contribute meaningfully to experience. This is true for the cerebellum, the ‘little’ brain at the back of the head, despite having more than four times more nerve cells than neocortex, the outmost convoluted layer of the brain. Even in neocortical tissue, the most complex piece of highly excitable matter in the known cosmos, the parts in the back have a much more intimate relationship to experience than others, such as in the front (prefrontal cortex) that are more related to reasoning, planning and intelligence.

Is the scientific study of consciousness getting anywhere?
Yes, many questions concerning consciousness are beginning to be answered by clinical and basic neurosciences. We can now safely and rapidly turn consciousness off and on again (for instance, using a variety of anesthetic agents). We are getting better at detecting its presence or absence in neurological impaired patients unable to signal, such as minimal conscious state or locked-in state patients using a consciousness-meter called zap and zip (a magnetic pulse is used to excite cortex and its response is measured across the skull using EEG electrodes). As discussed above, we can track the neuronal footprints of consciousness using brain scanners, EEG, microelectrodes and other devices and track its onset and disappearances in wake and during sleep in humans and in related species. And we can study consciousness in animals very different from us, such as bees or octopuses. This is real progress in the ancient mind-body problem.

Does consciousness have a function?
It may be true that in a narrow sense, consciousness does not subserve any evolutionary function. That is, it is certainly possible to imagine a creature just like us, but without any conscious experience what-so-ever. This is the fictitious zombie that David Chalmers and other philosophers use to argue for the impossibility of ever arriving at a fully satisfactory scientific account of consciousness.

However, consciousness appears to be closely intertwined with highly flexible and adaptive behavior and cognition, such as intelligence, memory, planning, self-reflection, language and so on. In that sense, consciousness could be a by-product of the selection of other characteristics. In evolutionary language this is known as a spandrel. Popular examples of spandrels are humanity’s wide-spread love of music or the ability to engage in higher mathematics. It is likely that neither music appreciation nor math skills were directly selected for in hominid evolution, but that they emerged when big brains made these activities possible.

Will AI ever be conscious?
Despite the near-religious belief of the digerati in Silicon Valley, most of the media and the majority of Anglo-Saxon computer and philosophy departments, there will not be a Soul 2.0 running in the Cloud. Consciousness is a not a clever hack. Experience does not arise out of computation. Siri 10.0 will never feel like anything.

The dominant mythos of our times, grounded in functionalism and dogmatic physicalism, is that consciousness is a consequence of a particular type of algorithm the human brain runs. According to one of the two dominant theories of consciousness, Integrated Information Theory, nothing could be further from the truth. While appropriate programmed algorithms can recognize images, play Go, speak and drive a car, they will not be conscious. Even a perfect software model of the human brain will not experience anything, because it lacks the intrinsic causal powers of the brain. It will act and speak intelligently. It will claim to have experiences, but that will be make-believe. No one is home. Intelligence without experience.

That’s the difference between the real and the artificial. A supercomputer simulating a rain storm won’t cause its circuit boards to become wet. Nor will a computer simulating a black hole twist and warp space-time around its chassis; you won’t be sucked into its simulated massive gravitational field. It’s the same with consciousness – clever computer programming can simulate the behavior that goes hand-in-hand with human level consciousness, but it’ll be fake consciousness.

That’s not to say there is something magical about brains; they are a piece of furniture of the universe like any other. A computer could acquire human-level consciousness, but it would have to be built in the image of the human brain, including its vast complexity, so called neuromorphic computers.

As this is the ‘Under’ issue, why are many concepts around consciousness expressed in terms of spatial relations, e.g. ‘going under’, ‘subconsciousness’, ‘a higher state’?
Great question! I think this is a specific instance of a general phenomenon – we have spatial metaphors for many aspects of mind – we move forward to an event in the future, we look back with regret at a lost opportunity, we fill our mind with ideas, the mind soars upwards. Most of these embody the idea of forward and upward being associated with the future and with higher aspects of mind; the converse is the Freudian sub-conscious and ‘going under’ during anesthesia.

Ultimately, these all reflect the universal phenomenology of space – whether defined in the visual, auditory or somatosensory modality – and the fact that we live on a planet with gravity that inexorably pulls us downward. Maybe as we make the transition from a planetary species to one where at least some of us of us are born in space and spend most of our life there, we will have fewer directional metaphors but even these future humans will have spatial metaphors as that is a universal aspect of existence of any organism.

What strikes you as remarkable about your own personal ‘feeling of life’?
I am continually amazed that I live in a universe that I can experience. Nothing in the foundational equations of physics, quantum mechanics and general relativity, in the Periodic Table and in the endless ATGC chatter of my genomes, is about consciousness. Yet here I am – seeing and hearing the world, being sad about the state of affairs or content when lost in play. That this should be so remains the fundamental mystery of our existence.

- Find out more about the book now.

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