|Posted by a.marlow on December 15, 2012 at 11:10 AM|
In recent years, the old philosophical problem of the nature of mind has become a subject of interest to physicists. Thinkers like Roger Penrose (author of 'The Emperor's New Mind' and 'Shadows of the Mind') and Stuart Hameroff have begun to suggest that the human brain works according to the same mechanisms as a quantum computer. Others have gone further, taking their thoughts to more esoteric levels and proffering that the human brain acts merely as a conduit, a transmitter, for an underlying and pre-existing quantum field of mind.
All of these ideas are fascinating- but there comes a time to move beyond the theory and the textbook, and to ask instead whether and how we may use these ideas in diagnosis, treatment and therapy; and, when this question arises, so too does the question of whether these theories even present an accurate picture of the human mind in the first place.
Into this quandary steps Nick Lane PhD, whose article in the Journal of the Royal Society of Medicine is the inspiration for this blog post. Writing from the perspective of a biologist, he pits the quantum view of consciousness and the biological view of consciousness against each other by viewing the fundamental requirements underlying each. A biological theory of consciousness simply demands an "extraordinary organisation of rather ordinary matter", while a quantum account would have to be based on "some very special properties of matter" in the form of "macroquantum effects". This is due to the fact that, while quantum physics almost perfectly describes the behaviour of matter at a subatomic level, Einstein's theories of relativity and Newton's laws of motion generally still hold water at the macro level; indeed, it is very rare to view the kind of effects generated by quantum mechanics at a micro level replicated at a macro level.
Lane admits that a complete and coherent view of consciousness based on the biological view is currently unavailable. He writes that:
"...all we must do is show that an enormously complex parallel processing system, comprising a hundred billion neuron-equivalents, coupled to a multifaceted and profoundly integrated sensory system, and an ability to remember and learn, is capable of giving rise to consciousness... That might take a while."
Yet if the biological account still fails to provide us with answers, Lane's view is that it is more likely to do so in the future than any nascent quantum theories currently on offer. What are these theories? Evan Walker proposes that consciousness is produced by delocalised electrons using cytoplasmic RNA as stepping stones and tunneling through synapses; Roger Penrose and Stuart Hameroff present a similar theory, except where microtubules take the place of Walker's RNA as the required intracellular structure. Yet Lane dismisses these theories, arguing that the probabilities of post-synaptic firing offered as evidence for Walker's viewpoint could just as easily be explained by conventional neurotransmission, and that the argument of Penrose and Hameroff (who claim that the key role of microtubules is shown by the way in which anaesthetic agents accumulate in them, implying that the ensuing loss of consciousness is related to an ensuing change in microtubule functioning) is discredited by the fact that anaesthetic agents also have effects on ion channel function and calcium influx, that there is no expert consensus on how anaestetics work (or even that they all work in the same way), and that certain chemicals, such as colchicine, are known to explicitly affect microtubules without having any effect on consciousness at all. Another theory, suggested by Ian Marshall, proposes that consciousness is generated by a coherent, non-local order of protein vibrations- "the melody of proteins singing together". Yet, as Lane points out, this particular theory also lacks any confirming evidence.
Each of these theories share another weakness: they all require specific molecular stepping-stones in order to be viable. For Walker, this stepping stone is a particular set-up of RNA; for Penrose and Hameroff, it is the presence of intact microtubules; and for Marshall, it is the existence of tiny gaps between vibrating proteins. Lane points out that the evolution of such specific systems is less likely than the evolution of a system whose only requirement for generating consciousness is a generally increasing complexity, as described by the biological account. He writes:
"...from a quantum broadcasting point of view, the machinery required to sustain consciousness must have evolved without compromising the computing function of the nervous system. Cells as highly specialized as neurons, which have evolved to a high degree of complexity even in organisms with little recognizable consciousness, cannot have much remaining flexibility to support the evolution of a new infrastructure for consciousness."
Because of this, Cairns-Smith has argued that neurons are bad candidates for ever being used to explain human consciousness, and that we should instead be looking to the less specialised glial cells of the brain, such as oligodendrocytes in the white matter or astrocytes in their support network throughout the brain.
Yet examining certain neurodegenerative conditions, even this hypothesis seems doubtful. In Multiple Sclerosis (MS), we see an attack on these very same oligodendrocytes- but no loss of consciousness. In Alzheimer's disease, we see early correlations between symptoms and neurofibrillary tangles in the neocortical association areas of the temporal lobe, such tangles being "but the ghosts of microtubules"- but again, no loss of self-awareness, with even advanced sufferers continuing to speak in first person and to respond to changes in their conversations and their environment.
In acute ischaemic stroke, however, there may be tentative evidence for some of Cairns-Smith's ideas. This kind of stroke sometimes brings about widespread depolarisation of astrocytes. A 1995 study of 24 patients who showed dramatic recovery from their stroke during a thrombolysis trial by Grotta & Bratina found that "most patients seemed peculiarly unaware or blasé about their deficit and improvement", perhaps implying that a sluggish recovery of the astrocyte network led to a sluggish recovery of their self-aware consciousness.
While Lane's article is certainly informative, but my major critique would be his working definition of 'consciousness', even if it is a somewhat orthodox one. He writes:
"For consciousness... I mean awareness or sentience, both of our own self and of our relationship to the world around us."
Yet this strikes me as a rather reductive definition. We tend to think of something that is not 'conscious' as being 'unconscious'. Yet there are many altered states of consciousness where one might not satisfy Lane's working definition above, but still be far more 'conscious' than 'unconscious'. Altered states of consciousness may be reached in many ways, whether through certain types of meditation, through use of illicit drugs or through experiential therapies such as Holotropic Breathwork. In these altered states, one may experience a loss of identity and individuality, often coupled with a sense of oneness and unity with the universe. One might also 'hallucinate' in such a way that an outsider would say you were 'seeing things that weren't there' when, in actual fact, a proper understanding of the experience would acknowledge the deep psychological meaning and healing potential of the visions. Crucially, these experiences, in which one ostensibly loses awareness of one's self and one's physical surroundings, are often experienced as being far more real than ordinary wakeful consciousness. The person going through them is not in a dream and could not be said in any sense of the word to be 'unconscious'. Therefore, while much of what Lane says in his article is fascinating and illuminating, a proper study of human consciousness cannot be undertaken while the background definition of the subject excludes states where one is quite clearly conscious in some sense of the term.
So, what of the question that started off this blog post? Despite his definitional deficit, Nick Lane provides an evidential background to the theory of the Quantum mind and shows it to be lacking. In this context, while the truth and mechanisms of this particular theory have yet to be established, there seems to be little we can take from it into the therapeutic situation.
Lane, N., 2000. "Medical constraints on the quantum mind", Journal of the Royal Society of Medicine, 93:571-575