Online Book 6

                                                                                                 A THEORY OF CONSCIOUSNESS

At this stage, we might think we have covered enough ground to try to put together a theory of consciousness that has explanatory power, and is not obviously at variance with what we know about physics, neuroscience or evolution.

We have tried to define consciousness, as our subjective experience, or as the fact of it 'being like something' to experience things. Consciousness also involves our subjective awareness of the real or apparent ability to subjectively envisage future scenarios, and to use these for our choice of actions. I have further suggested that there is only one problem with consciousness, the problem of how qualia or subjective experience arises, and that we have to address this and essentially only this in discussing consciousness.

We have examined theories of consciousness that operate within the context of classical physics, and always come up against essentially the same explanatory gap. Classical physics gives a full explanation of the relationships of macroscopic matter, without any need for consciousness, and also without any ability to generate consciousness. This creates a problem as to how the brain can generate consciousness, given that neuroscience describes the brain in terms of the macroscopic matter made up of carbon, hydrogen, oxygen and other atoms, the relationships of which can be described without either requiring or generating consciousness.

The failure to find a theory with satisfactory explanatory power within classical physics pushes us towards identifying consciousness as a fundamental or given property of the universe. What does this really mean? Explanation in science works by breaking things down into their components and the forces or processes that make them function. But this downward arrow of explanation does reach a floor. Mass, charge, spin and the particular strengths of the forces of nature are given properties of the universe that are not reducible to anything else and come without any explanation. Because consciousness has a similar lack of explanation, it is similarly suggested to be a fundamental property.

This is only a start. In itself it tells us nothing about how such a fundamental manifests in the brain. Rather than having a solution, we are only at the beginning of a very difficult journey towards something with explanatory value. Not only do we have to discover some system that is truly fundamental, but, given the lack of apparent consciousness in the rest of the universe, we need a process that is unique in operating only in brains, and not in other physical systems.

Quantum consciousness is really a misnomer for the sort of system that we are looking for. The philosopher, David Chalmers, was correct in pointing out that there was no more reason for consciousness to arise from quanta than there was for it to arise from classical structures. Both permeate the universe outside of the brain without producing consciousness. The quanta and their behaviour are only of interest if they can allow the brain access to a fundamental property not apparent in other matter.

This brings us also to the question of what really is fundamental. There are two sides to this question. The quanta and spacetime. The quanta are the fundamental particles/waves of energy, which also equates to the mass of physical objects. Some quanta such as the proton and the neutron are composed of other quanta, so are not truly fundamental or elementary. The quarks that make up the protons and neutrons of the nucleus of the atom and the force carrying particles such as photons appear to be the most fundamental quanta. But the quanta cannot be understood in isolation. They must be seen as having some form of relationship to spacetime, and that's a more difficult area than might appear at first sight.

Neither quantum theory, nor relativity which is our theory of spacetime, have ever been falsified, but they are, nevertheless, incompatible with one another. Many physicists are coming round to the notion that spacetime is not an abstraction but a real thing, and also something that is not continuous, but discrete, and perhaps best conceived in the form of a web or network. They are divided as to whether the quanta create spacetime, or spacetime generates the quanta, or the third possibility that the two are expressions of something more fundamental. However, whatever form it is conceived to take, the concept of a real and discrete structure also allows the possibility of some form of pattern or information capable of decision making, and this is the level of the universe where we need to look for an explanation of consciousness..

There are two routes leading to the conclusion that consciousness has to derive from such a fundamental level of the universe. In addition to the view that classical physics simply can't cut it in respect of consciousness, there is the Penrose approach via the function of consciousness. As described earlier, he proposed that the Gödel theorem meant that human understanding or conscious could perform tasks that no algorithm-based system such as a computer could perform. This is led to an arcane dispute with logicians and philosophers which few lay people can follow.

However, I think it unnecessary to penetrate into such an arcane area. At a much more mundane level, the process of choosing between alternative forms of behaviour or courses of action by means of subjective scenarios of the future looks to also invoke a process that cannot be decided by algorithms. This suggestion is now supported by recent studies showing that in the orbitofrontal region the brain some activity correlates to subjective appreciation rather than the strength of signal, whereas in other parts of the brain not involved with preferences, activity correlates to the strength of this same signal. So while Penrose provides the original inspiration for the idea of an aspect of the universe that could not be derived from a system of calculations, it seems possible to simplify or streamline the original inspiration in a manner that is compatible with recent brain research and not open to the same sort of attacks from logicians and philosophers.

In a similar way, it may be possible to simplify Penrose's proposal of a special type of quantum wave function collapse as the gateway to conscious understanding, seen here as an aspect of fundamental spacetime geometry. Penrose dismissed the randomness of the conventional wave function collapse as irrelevant to the mathematical understanding in which he was initially interested, and instead proposed a special form of objective wave function collapse, which was neither random nor deterministic, but accessed the fundamental spacetime geometry. His proposal as to wave function collapse is currently the subject of experimental testing although this is a procedure that is likely to take up to a decade.

Again the question is whether it is necessary to go to such lengths. Might there be a way around the apparent randomness that led Penrose do dismiss conventional wave function collapse. Might not the more conventional wave function collapse, or alternatively decoherence equally well provide an access to the fundamental and conscious level of the universe. There are queries as to how random the randomness is. In one form of the famous two slit experiment, single photons arrive at a screen over some extended period of time. The initial photons register on the screen in apparently random position, but as later photons arrive the familiar light and dark bands form. Somehow later photons or perhaps the earlier photons, 'know' where to put themselves. There is a suggestion that this puzzle links to one of the other puzzles of quantum theory, namely entanglement, by which the quantum properties of particles can be altered instantaneously over any distance. In this suggestion, the photons in the two slit experiment are entangled with other distant quanta. Whatever it is that decides the position of these particles in this scheme has no apparent explanation in terms of algorithms or systems of rules for calculating, and this is something that it holds in common with choice by emotional valuation.

But how could such a mechanism related to the fundamentals of distant space arise within our brains. Penrose's collaborator, Stuart Hameroff, proposed a scheme by which quantum coherence arose within individual neurons and then spread throughout neuronal assemblies. Most conscious commentators believe that this theory can be straightforwardly refuted because of the rapid time to collapse or decoherence for quantum states in the conditions of the brain. However, this simplistic approach has in effect been partly refuted by the discovery of functional quantum coherence in biological systems during the last few years, initially in simple organisms subsisting at low temperatures, but most recently at room temperature and in multicellular organisms. Moreover, it is now apparent that the structures of aromatic molecules within the amino acids of individual neurons are similar to those within photosynthetic organisms now known to use quantum coherence. The structures that support quantum states in photosynthetic systems rely on the pi electron clouds discussed in earlier sections and in microtubules the amino acid tryptophan supports the same structure of pi electron clouds which thus look potentially capable of sustaining quantum coherence and entanglement through significant sections of a neuron. The mechanisms by which quantum coherence could subsist in neurons looks here to be within our grasp or understanding.

But as with the original Penrose proposal, Hameroff's scheme may be more ambitious and therefore more open to criticism than it needs to be. Where quantum states have been shown to be functional they subsist for only femtoseconds or picoseconds, whereas the Hameroff scheme requires quantum coherence to be sustained for an ambitious 25 ms, moreover it has to be sustained over possibly billions of neurons spread across the brain. This lays it open to attack from many angles.

It looks much more feasible to work from the basis of quantum coherence that exists in other biological systems and to look for similar short lived single cell processes in the brain. The known systems of functional quantum states that subsist within individual cells elsewhere in biology look to have the potential to exist within neurons. For this reason, it is thus much more feasible in the absence of countervailing evidence to work on the basis of consciousness arising within individual neurons. This effectively inverts the Hameroff scheme. Rather than neurons feeding into the global gamma synchrony, the synchrony, which is certainly correlated with consciousness, may be a trigger to conscious activity in neurons.

Recent studies give credibility to the idea of consciousness in single neurons. Experimentation has shown that increased activation in single neurons is correlated to particular percepts. Some neurons are selective in only responding to particular images, and activity in these is correlated to the conscious experience of those images. Of course it isn't as simple as that. With 100 bn neurons in the brain, and perhaps a good percentage of these selecting for particular images, there has to be some way of coordinating their activity.

It is initially puzzling that the same type of experiments that show a correlation between consciousness and individual neurons, also show a correlation between the global gamma synchrony and consciousness. So which of these produces consciousness, the individual neurons or the gamma synchrony? Recent studies suggest that activity in individual neurons correlates with the gamma synchrony when a number of the neuron's neighbours were also active. This agrees with studies showing 'hot spots' of activity in the brain also correlated with consciousness. Here we are perhaps left with the concept that the brain is a gate to the fundamental level of the universe, in the literal sense of a mechanism that allows or prevents entry.

All of this may seem very speculative, but against this has to be set the lack of explanation in classical physics for the 'something it is like' or the ability to have choice or preference that we find in consciousness.