Chapter 13: Mind and Matter

from: The Quantum Mind by Prof. John Joe McFadden.

On July 18th, 1897, The Seattle Daily Times ran the headline, "At 3 o'clock this morning the steamer Portland from St. Michael for Seattle, passed up the sound with more than a ton of solid gold on board...". The news flashed around the world and within days, the greatest gold-rush the world has ever seen, headed for the Klondike.
The late 1890's had seen one of the deepest global depressions of modern times. Millions of men were laid off work; thousands of families were evicted from their lands and the homeless were left to starve in the streets. And then the SS Portland, steamed into Seattle harbour with its cargo of bright gold. Tales of snow covered fields sprinkled with gold dust, swept across the world and within days, tens of thousands of men and women sold what possessions they had, to book passage to the Klondike.
Most were not professional prospectors but unemployed bank clerks, farm labourers, dentists, anyone young enough and desperate enough to chance their luck. Few had any knowledge of gold prospecting, or the fact that they would have to face one of the most arduous journeys in the world, before reaching the Klondike. Many headed north to the Southeast Alaska town of Dyea and the start of the 32-mile long Chilkoot Trail, their first and harshest test. Prospectors had to carry a year's supply of food for the journey, which together with their equipment, weighed about a ton. The first stage was a 3,550 feet climb up the mountainside, with each man having to make as many as twenty successive trips to haul all their load. And that was only the beginning of their journey. Before they reached the Klondike they would have to travel for months across snow-capped mountains, frozen lakes and crevasse-laced glaciers, and endure temperatures that dropped to fifty degrees below freezing. Many became so physically exhausted that they sold or abandoned their goods and turned back. Many others died on the trail, having fallen into crevasses, been buried under avalanches or been murdered by bandits. Those that did make it founded the town of Dawson that still stands today on the banks of the Klondike. Though today a sober and respectable town, in the 1890's it was a notorious northerly outpost of the Wild West lifestyle where most prospectors lost their remaining money and possessions to a host of thieves, gamblers and con-men.

The above picture, by Asahel Curtis, is one of the most striking images to depict the power of the human will. The whole history of man's struggle to impose himself on a hostile environment seems to be written in that thin black trail of humanity trudging over the Chilkoot Pass. Our will - our ability to make decisions and direct our own actions - has surely been our most valuable and dangerous asset in that long road from the primeval forests to our modern cities. Without it, we would never have fashioned tools, planted crops, tended herds, built cities or forged weapons to destroy crops, herds, cities and people. There would be no civilisation, no lofty buildings, no beautiful paintings, no sublime music and no books about the origin of all these things. Each of these achievements takes some effort against the tide of inevitability. Our will is surely the most striking manifestation of life's ability to perform directed actions. But where does it come from?
Consider the scene in the picture as it might have been witnessed by the imaginary alien spacecraft that we met in the first chapter. At daybreak it would spot a thousand tons of amorphous material - perhaps a mass of 'rock' (though in reality people and supplies) - lying at the foot of a mountainside. By dusk, that same material would have been elevated by several thousand feet. The spacecraft would have been left with a problem: how to explain that this mass of rock managed to increase its potential energy so enormously as to elevate itself up the mountainside. It would have first looked for some external agency acting upon the rocks, capable of raising them several thousands of feet against the force of gravity; but it would have found none. It would next have attempted to account for the feat in terms of the internal dynamics of the system, perhaps as some spontaneous physiochemical reaction. As we discovered in Chapter 5, Newtonian mechanics and its statistical cousin, thermodynamics, govern the motion of inanimate material. To account for the Chilkoot climb in purely mechanical or thermodynamic terms, the alien spacecraft would have had to suppose that all of the molecules in the rocks and their surroundings were so arranged that their random bumping and jostling (which is of course, all there is to thermodynamics) caused the entire rocky mass to ascend spontaneously up the mountainside. Is such a view tenable? Could random mechanical and thermodynamic forces have accounted for the climb over the Chilkoot Pass?
I am sure that you will not be surprised that I believe the answer to that question is no. The alien spacecraft would recognise, in the Chilkoot scene, the same signature of life that it spotted in the bird soaring into the sky or a salmon leaping a waterfall: the ability of living organisms to initiate directed actions. But how does the human will cause the motion of bodies on such massive scales? To attempt to answer to this question we need to explore how we will our bodies into action.

How nerves move muscle

In Chapter 5, I described how our voluntary muscle cells contract when we kick a football. The same kind of muscle contraction similarly accounts for the ability of the Klondike prospectors to drag themselves and their supplies up a mountainside. But what causes muscles to contract in response to the will of the prospector? How do we will matter (our muscles) to move?
We have already seen (Chapter 5, Figure 5.5) how the mechanical energy for muscle contraction is provided by the hydrolysis of ATP by myosin molecules. But what causes myosin to hydrolyse ATP and thereby initiate muscle contraction? The immediate answer is calcium. Raised calcium levels trigger the enzymatic activity of myosin. The raised calcium levels are caused by a release of calcium from intracellular calcium stores in response to electrical depolarisation of the muscle cell membrane.
Most cell membranes are electrically polarised, with more positive ions outside the cell than inside, leading to a negative voltage across the cell membrane. However, membranes can depolarise if positive ions are allowed to travel through pores in membranes to neutralise this voltage difference. Muscle cells and nerve cells have special kinds of pores - known as voltage-gated ion channels - that open and close in response to changes in the voltage difference across cell membranes. They remain closed so long as the voltage difference is sufficiently negative but they pop open whenever that electronegativity drops below a critical threshold. Yet throwing the channels open only lets in more positive ions to cause a further drop in the membrane voltage thus popping open more voltage-gated channels and precipitating a rapid cascade of depolarisation. This accelerating membrane depolarisation - called an action potential - stimulates the release of intracellular calcium stores within muscle cells and so initiates muscle contraction.
The next backward step in our chain of causation from the prospector's leg, is to understand what causes the initial electrical depolarisation that opened the voltage-gated channels in his leg muscle. This is where nerves enter the picture. Motor nerves (nerves that stimulate muscles) terminate in structures called synaptic knobs (Figure 12.2) that abut against the muscle cells at neuromuscular junctions. The synaptic knob releases a chemical signal (a neurotransmitter) into the fluid-filled space between the nerve cell ending and the muscle cell: the synaptic cleft (Figure 12.1). Different types of nerve endings release a varied bunch of neurotransmitter signals, but most motor nerves release a neurotransmitter called acetylcholine. Muscle cells have acetylcholine receptors embedded in their membranes that act as ligand -gated ion channels. Whenever these receptors capture a molecule of acetylcholine (released by the synaptic knob of the nerve cell), they transiently open a channel for sodium ions to flow into the muscle cell. If enough ligand-gated channels are opened to allow in lots of sodium ions, then the membrane potential sufficient will be reduced below the threshold needed to pop open the voltage-gated ion channels and thereby initiate the action potential.
So the voltage-gated ion channels that kick the muscle into action, are opened up by the action of another set of channels - the ligand-gated ion channels - that respond to neurotransmitters released into the synaptic cleft. Our next backward link is then to understand what makes the motor nerve cell release those neurotransmitter molecules. The synaptic knob of the motor nerve cell is full of tiny vesicles filled with thousands of molecules of acetylcholine. The nerve cell discharges the contents of these vesicles into the synaptic cleft, whenever an action potential arrives at the synaptic knob .
Action potentials are fundamental to nerve action, so we need to take a closer look at them. Nerves (or neurones) are very long cells (can be more than one metre long) with a spidery cell body at the head-end of the cell, connected by a long axon to the tail-end of the cell: the nerve ending or synaptic knob that releases neurotransmitter molecules . Signals are communicated along nerves by action potentials that travel along the axon from the cell body to the synaptic knob. The axon looks a bit like a thin wire so you might think that nerve impulses would be transmitted by a flow of electrons, just as electrical signals are passed down a metal wire. But you would be wrong. Nerve transmission is very different! Like muscle cells, neurones in their resting state have a voltage difference across their cell membrane that is maintained by a sodium pump that pushes positively-charged sodium ions out of the cell. Normally the voltage difference is about minus 65 millivolts (positive outside, negative inside), which may not sound like very much but since cell membranes are less than one thousandth of a millimetre thick, it amounts to a staggering 13,000 volts per centimetre. Also like muscle cells, neuronal membranes have voltage-gated sodium channels that open up whenever the voltage drops below about -40 millivolts. To see how action potentials are propagated, imagine first that a few of these voltage-gated channels are already opened at the cell body (the head-end) of the nerve (Figure 12.2). Positively charged sodium ions will rush in through the channels, to reverse the voltage difference across the membrane and cause membrane depolarisation. When the voltage dips below -40 millivolts (for this to happen thousands of channels must open) then adjacent voltage-gated ion channels will also be provoked into popping open. This will cause another surge of sodium ions to enter the cell and the further depolarisation will stimulate the next set of membrane channels along the axon, to open their doors. This process will continue as a wave of membrane depolarisation - the action potential or nerve impulse - that travels from the cell body along the nerve axon, at a rate of about 100 metres per second, until it reaches the synaptic knob.
But we have so far just imagined the initial membrane depolarisation caused by the opening of a few sodium channels. What normally opens these channels to causes the neurone to fire? Mostly it is other nerves. The cell body of a motor nerve is located in the spinal cord. It possesses long spidery extensions called dendrites (Figure 12.1) that are the targets for synaptic knobs of connecting nerve cells. The upstream synaptic knobs release their load of neurotransmitter into the synaptic cleft to be picked up by receptors on the dendrite extensions of the motor nerve cell body (Figure 12.1). How the motor nerve cell body interprets the neurotransmitter signal varies greatly, depending upon the type of neurotransmitter. Some neurotransmitters will open ligand-gated ion channels, whereas others will close them. If the cell receives enough 'open' signals, then sufficient ions will enter the cell body to decrease its membrane potential below the critical threshold of about -40 millivolts and pop open the voltage-gated ion channels to initiate the action potential.
So the neurone is a democrat. It will decide whether or not to fire on the basis of balance of neurotransmitter votes that it receives.

How our brain moves nerves

Each nerve cell is an information processing centre: it has an input (usually synaptic signals from other nerves), an information processing centre (the cell body) and an output (to release neurotransmitter or to not release neurotransmitter into the synaptic cleft). The cell bodies of most voluntary motor nerves (whose nerve endings terminate at neuromuscular junctions) are located in the spinal cord where they form synapses with sensory neurones (mostly through an intermediary interneurone) and neurones from the brain. If you are unlucky enough to stand on a nail then your leg muscles will immediately contract to withdraw your foot, in an action known as the flexor reflex. This reflex is initiated by a signal from sensory nerves in your foot, which registers the breaking of the skin (sensory nerves have modified cell bodies that directly register physical signals, such as light, heat or touch, instead of receiving signals from another cell). The nerve signal races up your leg and enters your spinal column, to be transmitted (via an excitory interneurone) to the motor neurone. The signal is thereby transmitted from your foot to your calf and thigh muscles, without any involvement of your brain (although a pain signal is also sent to your brain, but this arrives after the initiation of the reflex).
However, our prospector's first step up the mountainside was unlikely to have been a reflex (unless he happened to tread on a nail). It was a voluntary action; and voluntary actions are initiated in the brain. The human brain is undoubtedly the most complex biological system that has ever evolved on this planet and may indeed be the most complex organised system in the entire universe. However, the observant reader will surely have spotted that the remaining pages of this book are few and will no doubt be aware that the problems of the human brain are many. They will be sceptical of any attempt to tackle that great bastion of anatomy, neurophysiology, psychology and indeed philosophical speculation, in the remaining pages of this book. They are right to be sceptical. The brain and its most mysterious occupant - our own consciousness - is a vast topic to cover in an entire volume, let alone a single chapter. There are many excellent and interesting texts (some mentioned in the bibliography) that deal with the brain and its functions in the kind of detail that is more appropriate to the complexity of that topic. However, I will try to limit our exploration of the brain to the very minimum needed to explain why I think we need quantum mechanics to account for the actions performed by our gold prospector.
Our brain consists of about one hundred billion (1011) neurones and about a trillion (1012) non-nerve cells, known collectively as glia. A great deal of evidence has accumulated to indicate that it is within the thin sheet of cells that forms the cortex of the brain (the cortex is that grey wrinkled layer that forms the outermost surface of the brain and is only about six cells thick) - wherein most of information processing takes place. The Canadian neurosurgeon Wilder Penfield, working in the 1930s through to the 1950s, performed pioneering studies to map those regions of the cortex involved in various sensory and motor activities. Penfield was able to electrically stimulate discrete areas of the cortex of patients undergoing brain surgery. Remarkably, because the brain has no pain receptors, the operations could be carried out under local anaesthetic, allowing the patients to describe to Penfield the sensation they experienced when particular regions of their cortex were stimulated. Penfield was able to map the cortical areas involved with touch sensory perception (when these areas of the somatosensory cortex were stimulated, the patients would experience a tingling sensation); visual perception (when these areas of the visual cortex were stimulated the patients would see bright lights); and voluntary movement (when these areas of the motor cortex were stimulated the patient's arm or leg would twitch). Even more remarkable was Penfield's finding that when he stimulated the area of the brain known as the temporal lobe (located on the lower surface of the brain, under the temporal bone) patients would hallucinate or recall long forgotten incidents (the patients would say something like, "I feel as though I were in the bathroom at school"). It appeared that Penfield was reactivating long-forgotten memories that were stored in the temporal lobe.
So the nerve impulse that initiated our prospector up the mountainside would have had its origin in a neurone or assembly of neurones within his motor cortex. But what caused the critical neurone to fire? Like most other nerve cells it must have had many inputs from other neurones. The dendrite extensions of brain nerve cells are massively branched, forming synapses with thousands of other nerve endings to form a dense integrated network of neurones. The critical motor neurone in our prospector's brain would certainly have had plenty of inputs from neurones in the somatosensory cortex, the visual cortex and many other regions of the brain. Each of those inputs would have had its own input nerve cell. That nerve cell in turn must have its input neurone and that neuron must have its input neurone and so and so on backwards through an infinite regress of outputs and inputs! Where does the buck stop? Which neurone takes the decision whether or not to fire our gold prospector up the mountain?
If man was a machine, a robot, we could easily envisage a simple stimulus-response mode of muscle firing. Man sees mountain, eye sends signal to brain (along sensory nerve), brain sends signal to muscle. Voluntary movement is clearly not this kind of reflex action but must depend on more complex signalling and information processing between the stimulus and response. Consider the gold prospector, paused at the foot of the Chilkoot Pass. With one hundredweight of supplies on his back, he looks up at the expanse of snow and ice and considers the long weeks of cold and hardship he must endure before reaching the Klondike. He sees visions of gold lying in the snow but he also sees smoke from the log fires burning in the cabins below. Does he take his first great stride up the slope or does he instead turn back towards warmth, comfort and failure? If we could have asked one of those prospectors who made it to the top of the Pass why he took that first step, he would have told us of his dreams: the smiling faces of his wife and children when he returns laden with riches; the house he would buy; the clothes he would wear; his proud expression as he would stride triumphantly down the main street of his hometown. He would certainly not describe his actions in the same terms he would use to explain how he leaped after treading on a nail. He would have assured us that he had made a conscious decision to climb that hillside. Was he right?

How consciousness moves our brain

We feel that we consciously will our voluntary actions, but how can something as ephemeral as consciousness move our muscles? To initiate muscle contraction, our conscious will must stimulate neuronal firing within the motor cortex of our brain. But the opening of ion channels in the cell membrane of nerve cells causes neuronal firing. These ion channels are made of the same kind of protein that one finds in a peanut. The power of our will (without aid of muscles) cannot move the proteinaceous matter of a peanut, so how can it move the same kind of matter (ion channels made out of protein) when that matter is inside my brain? How does mind move matter?
This question, often referred to as the mind-body problem, goes back at least as far as the Greek philosophers. You may remember from Chapter 1 that Aristotle considered the body to be made of matter but the immaterial psyche or soul initiated the movement of that matter. Aristotle believed that the seat of the soul was the heart, the brain's function was merely to cool the blood. That influential Roman physician to the gladiators, Galen, taught the modern view that the brain was the seat of knowledge, intelligence and will. Galen proposed that voluntary movement is initiated by the motion of humours within the fluid-filled ventricles of the brain and these disturbances travel down the nerves - which he thought to be hollow fibres - to the muscles.
The concept of the brain as a mechanical pump appealed to the mechanists of the 17th and 18th century, but even their champion, René Descartes, could not accept that the basis of all human actions was mechanical. Instead he advocated what has come to be known as the dualist tradition, that the human mind is composed of the material brain and also an immaterial mind or soul, whose spiritual substance lies outside the realm of science. The brain's job was to perform all the mechanical tasks that we share with beasts, like walking or eating, but our incorporeal mind was held to be the seat of thoughts, feelings and conscious actions.
Most modern scientists reject dualism and instead embrace monism: that the stuff of mind is the same as the stuff of brain, matter. Many consider that the brain works in essentially the same manner as any modern computer, but it is more complex and may be wired somewhat differently. We will next examine that hypothesis.

The Computing Brain

Our brain certainly has impressive computational skills but is it a computer? To answer this question we need to know just a little about how computers work. All modern computers are composed of tiny electrical circuits (called bits = Binary digIT) which send a signal that can be either ON or OFF. A logic gate is a circuit that combines these signals to perform a particular logical operation. For example, an AND gate has two input signals and a single output. If its inputs are both ON, then it switches its output to ON. An OR gate will switch ON if either of its input circuits are ON. Computers perform calculations by combining the logical operations performed by gates to perform the necessary additions, subtractions, multiplications, etc. and arrive at an answer. The sequence of logical operations used to perform a particular calculation are termed algorithms.
A major difference between the neurones in our brain and modern computers is that a computer logic gate has few input circuits (usually two) whereas a single neurone may receive input from thousands of upstream neurones. Yet it may still perform the same kind of algorithmic computation as a computer: fire only if all input neurones are ON (an AND gate), or fire if any input is ON (an OR gate). A complex network of gates may perform the detailed calculations necessary to decide whether or not to initiate a certain action. The decision-making neurone of our gold prospector will have received signals from his visual cortex and somatosensory cortex that contained information concerning the steepness of the slope, the weather, temperature and the tiredness of his limbs. These inputs will have been processed during their passage through a complex network of neuronal gates before arriving at an answer: to stimulate or suppress the critical neurone's firing. Returning to the Chilkoot, we will imagine that the weather was particularly fierce on the morning of our prospector's decision so most of the sensory inputs' synaptic knobs released inhibitory neurotransmitters towards the decisive motor nerve. Stimulatory signals may have arrived from other parts of the brain, perhaps those concerned with memory. Our prospector's temporal lobes might have held images of a hungry child or a wife dressed in rags and these would have been processed to send signals to urge him forward in his search for gold. Once the decisive neurone had received all its inputs, it might have performed a simple calculation: add up all the stimulatory signals, subtract the inhibitory signals and if the answer generates a membrane potential less than minus 40 millivolts, then get up that mountainside!
But what then is the purpose of the prospector's consciousness, if all his decisions are determined by brute neuronal calculations? Why does he need to be aware of his actions if their cause is neuronal number crunching? Wouldn't an unconscious computer do the job just as well? A fundamental principle of computing is that the algorithms performed by one algorithmic computer can in principal be run on any other algorithmic computer . If a computer were built to go though the same algorithmic routine as those utilised by our prospector's brain, would the computer also be conscious? Many computer scientists take the view that it would. They consider that consciousness is just a by-product of extremely complex computation; and that any computer that could perform the kind of algorithms that a gold prospector performs, would inevitably become conscious. But why should it? It would serve no function. Consciousness would have no role to play in the computer's decision-making process. A conscious computer would perform the same calculations and make the same decisions as an unconscious computer. Does consciousness similarly play no active role in the decision-making process taking place within our brain? Would an unconscious zombie make the same decisions as our gold prospector ? Are we just automatons that happen to be aware of our actions because of some evolutionary accident? In the words of the evolutionary biologist T.H. Huxley, is consciousness like the 'steam whistle which accompanies the work of a locomotive [but which] is without influence upon its machinery'?

Initiating actions

Most readers, would I guess, like myself, be reluctant to relinquish a role for our conscious free will. We all feel that there is a mind inside our heads that has the power of volition over our actions. Yet, experiments performed by the American neurobiologist, Benjamin Libet, of the University of California, profoundly challenge this belief. With the neurosurgeon Bertram Feinstein, Libet performed a series of fascinating studies on the timing of both sensory perception and motor actions. Although many of his experiments were performed intracranially on patients undergoing brain surgery, it was a simpler, less invasive procedure that yielded one of his most startling findings. Libet asked normal healthy subjects to flex their finger at some time of their own choosing. He placed electrodes on the subject's scalp, to record their brain's electrical activity associated with this action. The subjects would also record when they thought they had initiated the action by noting the position of a rapidly rotating clock hand. Libet would monitor the motor action by recorders attached to the person's limbs. It takes only a few milliseconds for a nerve impulse to pass from brain to muscle, so this is pretty good marker for initiation of motor neurone firing in the brain.
Subjects reported their awareness of making a conscious decision to move, about 200 milliseconds before that action was recorded at their muscle. The timings indicate that there is generally a delay of about 200 milliseconds between the time at which we become aware of our intention to perform a conscious action and firing up the appropriate motor nerve. However, what was much more surprising was that Libet routinely detected neuronal activity in the brain associated with the voluntary action, a full 300-400 milliseconds (nearly half a second), before the time when patient reported that they had made the decision to move. These apparent voluntary actions were initiated well before the subject's knew they had made any conscious decision to act!
At first sight this experiment seems to demonstrate that we are automatons. Voluntary actions are really unconscious acts that we retrospectively become aware of. In this view, the decision to send our prospector up the mountainside was made well before he knew where he was going. His brain performed some kind of complex calculation of the pros and cons of each option, sent him up the mountainside (or not), and only later, made him aware of his actions.
Is free will therefore an illusion? Are we slaves to the unconscious neuronal activity of our brain? Where does that leave our sense of responsibility, our conscience, our pangs of guilt, or pride in our actions; are they are all delusions? Have we the right to punish wrong doers, if they could not help their actions? But then we are also unable to help our own actions in punishing them!
Man, as an aware but helpless robot is a depressingly bleak vision of the human condition. Fortunately, it is not necessary. Libet's experiments did not compel him to abandon the notion of free will. Instead he proposed that consciousness acts to modify or veto actions that are initiated unconsciously. Neuronal activity may precede a conscious decision to act, by 300-400 milliseconds; but (and crucially) there was still a gap of 200 milliseconds or between the awareness of a conscious intention to act and the initiation of the motor impulse. Libet proposed that it is in this motor lag period that consciousness can have an influence on voluntary action. Voluntary actions may be initiated unconsciously but, before they are consummated, consciousness may intervene to veto or reinforce the action and thereby restore free will. Libet found evidence for this veto by observing the kind of neuronal activity that is often followed by motor action, was sometimes aborted, before that action was completed.
This explanation makes a lot of sense in terms of my own experiences. I can remember watching that particularly startling scene in the 1979 movie "Alien", when the monster bursts out of John Hurt's stomach. Like many others in the audience, I 'started' to cry out, only for that action to be vetoed by my conscious mind (which knew I was in a crowded cinema). I am sure there are many similar occasions when your own conscious mind similarly asserted itself, to interrupt a potentially embarrassing voluntary action (we often describe those who are less able at this skill as people who are always putting their foot in it).
So much of the computational work concerned with initiating the motor actions that took our prospector up or down the mountainside would have been initiated unconsciously, but there was still a window (of about 200 milliseconds) when his conscious mind could have intervened to reinforce or veto any action. That brief window of consciousness is the entry point for our free will. We must next explore what can be seen through that window.
Binding our thoughts
If we were to ask our prospector why he needed to be conscious to make his decision to climb or not to climb the mountain, he would have no difficulty answering. He would have described all the factors that could influence his decision: the snow on the mountains, the howling of the wind, the cold, the weight of his backpack, the tiredness of his limbs, the likelihood of success, the dangers and the potential rewards. Whilst making his decision his conscious mind would have been aware of all these varied inputs as a continuous stream of information. How did all that data fit into his conscious mind?
We take for granted the unity of our conscious experience but it is extremely difficult to account for. The brain of our prospector would have received sensory information from his ears, nose, skin and muscles. Dedicated centres of his cerebral cortex (somatosensory cortex, auditory cortex, visual cortex, etc.) would have processed those streams of information. His memories would have been held somewhere else (perhaps in the temporal lobe); and the calculations he made on the value of gold or the cost of his supplies might have been performed in his frontal lobe. Even a single sensory input, such as his vision, would have been processed in different areas of the visual cortex. The man might see a grey rock tumbling down the slope but the greyness would have been encoded in one area of the visual cortex, the shape of the rock in another, its texture in another, its motion in yet another. But the man did not see: grey + round + rough + moving; he saw a rock tumbling down the slope. How did the prospector's brain integrate all this diverse information into a single conscious experience?
Consciousness appears to be parallel, in the sense that we can be aware of many items at once (think of how much information is contained within a single visual field) , but serial in the sense that we have just a single stream of consciousness (we can't think two thoughts simultaneously). How does this serial parallelism work? Can a machine's mind similarly monitor parallel streams of information? Consider your TV set which, depending on where you live and what kind of receiver you have, might be able to receive signals from anything from one to several hundred channels. However, unlike our brain, your TV can be tuned to only one channel at a time. Even the complex image projected onto our television screen is something of an illusion. In reality the TV processes only a single signal (equivalent to a zero or one) at any moment in time and thereby fires (or does not fire) a stream of electrons at a particular spot on the screen. It paints the image on the screen by performing this action thousands of times a second; and the relatively long duration of the consequent scintillation of the screen does the rest. But if we could ask the brain of our TV set what it was looking at, at any moment in time, it would describe just a single dot.
A slightly more realistic model of conscious brain activity would be a group of five sensory devices (video camera, microphone, etc., corresponding to the five senses) that record different aspects of the external world and feed their signals into a computer for analysis. But this will leave us with five independent streams of information to be processed by five independent computers. To integrate the parallel streams of information we might use a parallel computer. Your desktop PC is likely to have only a single linear processor, but parallel computers have many processors that are capable of performing multiple calculations simultaneously. The brain of IBM's RS/6000 "DeeperBlue" supercomputer that defeated the great chess grandmaster, Garry Kasparov in 1998, was built from 32 parallel processors that independently performed the various computational tasks associated with calculating each chess move. We might similarly integrate the information from all of the sensory devices by digitising their signal and feeding them into a parallel computer. We could program our parallel computer to perform a certain action whenever it received a certain combination of stimuli from its sense organs. To give the computer a little more character we will install it into a robot - we will call him 'Gold Digger Mark I' - and program him to march whenever he saw an image of the Klondike Pass on its video channel and heard the sound of howling winds from its microphone. Is this how the brain of our brain prospector made his decision as to whether or not to climb the mountain?
This question is harder to call because, on the face of it, Gold Digger Mark I would be able to make the same kind of decisions as the prospector. But this is to ignore our own subjective experience of our consciousness, which appears to be very different from the machinations of even a parallel computer. Parallel computers aren't really parallel in the way our consciousness appears to be parallel. When the Deeper-Blue supercomputer thought, each of the parallel streams of information from the independent linear processors was fed (as a single linear sequence of binary digits) into a (serial) controlling processor. This central processor looked at each input in turn and performed a calculation (algorithmic routine) to transform that input into a number (to be stored in its memory), before turning to the next stream of information. In reality, parallel computers are nothing more than a bunch of serial computers strapped together with another serial computer sitting on top to integrate the streams of information.
Gold Digger's brain would similarly be aware of only a single steam of binary information. But the prospector was not aware of one rock on the mountain, then another, then another followed by the sound of the wind then the temperature and so on. His conscious mind appeared to be aware of all these inputs at once as a single integrated view of reality. What is seeing all this information?
Scientists and philosophers used to imagine a part of the brain that watched all of the streams of sensory data: the Cartesian Theatre, as it came to be known. Rene Descartes even proposed a site for this theatre, the pineal gland . But there is no evidence for any such a privileged area in the brain and most scientists believe that consciousness is more diffusely located in the brain as part of a distributed network of neurones. We could mimic this kind of distributed neuronal network within Gold Digger's computer console by wiring each of the independent processors together so that they - by their interactions - generate the final output. Gold Digger Mark II would then have what is termed a neural net that more closely models the connectivity of the brain. Neural nets have of course been built and they show many interesting characteristics that are reminiscent of brain activity. They can, for instance, be trained to perform a difficult task, such as pattern recognition. As before, we could train our Gold Digger Mark II's neural net to respond (march) whenever its video camera saw a mountain and its microphone recorded the sound of howling winds. Does the neural net's awareness mimic our conscious awareness of parallel streams of information in the brain?
Many neuroscientists believe that it does - that consciousness is a by-product of the fantastic level of neural net interconnectivity in the brain. For instance, the neuroscientist Marcel Kinsbourne: 'Being conscious is what it is like to have neural circuitry in particular interactive functional states' . The problem with this explanation is again: why should it? We know that much of the complicated work that our brains performs never makes it to our consciousness. For instance, an accomplished violinist playing directly from a musical score will perform the complex neural calculations required to direct her hand, arm and upper body movement, without being conscious of this dense mass of calculation. Yet tap that same violinist on the shoulder whilst she is playing and she will become acutely aware of your interruption. What is the difference between complex neural nets that are conscious (that register the tap) and those that may be equally or even more complex (those that direct playing of the violin) but are unconscious?
It is hard to dispel the impression that consciousness represents an altogether different kind of operation, than the one that drives unconscious actions. Most of the time I drive my car more-or-less unconsciously, allowing my unconscious mind to perform all the necessary calculations concerned with turning the wheel or depressing brake to follow the twists and turns of the road. I am not really aware of these actions; I might be listening to the radio or thinking about some problem at work. However, if I happen to spot a hazard sign in the road - perhaps SLIPPERY ROAD AHEAD - then my conscious mind will seem to take control to drive the car. The radio will be forgotten and my conscious mind will instead take over the task of moving my limbs. What is it that is taking control in these situations?
There are many explanations of consciousness and it would take several volumes to do them justice. I refer the interested reader to many excellent books that give the theories a fairer hearing . However, in my opinion, none of them offer an explanation that adequately accounts for the fundamental problems of consciousness: what is awareness; how is our apparently serial mind aware of so many things at once; and how do we will actions? One of the most intriguing explanations of consciousness that has appeared in recent years - and one that has obvious relevance to this book - is that consciousness is a quantum mechanical phenomenon.

The Quantum Mind

The Oxford mathematician and physicist Roger Penrose proposed in his 1989 book, "The Emperor's New Mind", that the mind is a quantum mechanical phenomenon. Penrose believes that the phenomenon of conscious actions is intimately tied up with that great mystery of quantum mechanics: the reduction of the wave function, that we discussed in earlier chapters. Many other scientists have also opted for a quantum theory of consciousness. In her book, "The Quantum Self", the American scientific philosopher, Danah Zohar presented a case for a kind of quantum mechanical holistic psychology. Zohar's husband, Ian Marshall, proposed that the physical reality of consciousness was some kind of neuronal Bose-Einstein condensate in the brain. More recently, the Scottish chemist, Graham Cairns-Smith (famous for proposing that life originated in replicating clay minerals) took up this idea in his book, "Evolving the Mind". And, as I mentioned in Chapter 10, Anwit Goswami and Dennis Todd proposed that adaptive mutations and conscious volition have a common quantum mechanical source.
There are many aspects of quantum mechanics that are attractive from the point of view of an explanation of consciousness. The indeterminism of quantum measurement affords us some means of escape from Newtonian determinism - perhaps a place for our free will. In the words of the Hungarian-born physicist and inventor of the hydrogen bomb, 'According to quantum mechanics we cannot exclude the possibility that free will is a part of the process by which the future is created.' Quantum coherence may also help to overcome the binding problem by entangling diverse information into a single coherent quantum system. Many physicists, such as Eugene Wigner (see Chapter 9), had already recruited consciousness to serve as a collapsing agent in quantum measurement. If consciousness can explain quantum mechanics then perhaps quantum mechanics can explain consciousness! And allowing quantum mechanics into the brain opens up the intriguing possibility that the brain may in fact be a quantum computer.
In 1982 the physicist Richard Feynman first considered the possibility of computing with quantum objects. However, it wasn't until David Deutsch of the University of Oxford showed that a quantum computer was feasible, that the field of quantum computing really took off. The unit of information of a quantum computer, the qubit, is like a conventional computer bit but instead of having to be in a single state at one time (either ON or OFF), the qubit can exist as a quantum superposition of both ON and OFF simultaneously. This quantum parallelism potentially allows quantum computers to perform multiple algorithmic tasks simultaneously. A quantum computer could solve in seconds problems that would tax a conventional computer for many years.
But if quantum computers are so wonderful, why don't we all have them on our desktops? The reason is that quantum computers are extraordinarily difficult to build. The problem is decoherence. Quantum computers have to remain coherent long enough to perform a calculation and to report the answer to the outside world. Yet, as I described in the earlier chapters, quantum coherence is difficult to maintain for complex systems (like computers or brains) because the quantum particles inevitably become entangled with their environment. At the time of writing, scientists have just managed to construct quantum computers with a 2-qubit brain, consisting of a pair of beryllium atoms cooled to temperatures a whisker away from absolute zero. We are still a long way from a working computer.
Is it possible that our brain is at this moment performing the kind of computational activity that has eluded many of our most brilliant scientists for more than a decade? Yes it is. There are many precedents for nature discovering a technology well before man's inventions (for instance, flight). But if the brain is a quantum computer, then what are its qubits, its units of quantum information? Neurones are generally accepted to be the units of brain information but they do not look like credible candidates for quantum systems. Each neurone firing involves the motion of billions of particles in a highly complex environment. The massive levels of environmental entanglement this must entail would almost certainly cause very rapid decoherence. It is very doubtful that a neurone could exist as a quantum superposition for long enough to perform quantum computation.
Stuart Hameroff and Roger Penrose have proposed that the microfilaments within neurones may instead be the qubits of quantum brains. We have already met microfilaments in Chapter 5, as the actin tramlines on which the myosin motor protein travels along. Neurones also have actin microfilaments and also slightly thicker filaments, known as microtubules, which are made up of long strings of the protein tubulin. Like all proteins, tubulin has an electrical dipole (an asymmetric charge distribution, see chapter 5); and it can exist in a number of conformational states. Hameroff proposed that flipping between conformational states causes electrical disturbances that propagate along the length of the microtubules to transmit information. Penrose and Hameroff went on to propose that these electrical excitations may cause coherent oscillations within and between neurones and thereby act as the qubits of a neuronal quantum computer. In their view it is the microtubules, rather than neurones, that represent the fundamental computational unit of the brain.
I must admit to remaining unconvinced by the proposed role of microtubules in neuronal computing. They do not appear to be either sufficiently isolated or stable to remain quantum coherent. Microtubules have well defined roles in neurones; they are the tramlines for the transport of material (such as neurotransmitter) up and down the axon. A biochemical motor called kinesin - a bit like the myosin motor - runs up and down the microtubules carrying vesicles filled with neurotransmitter from the cell body to the synaptic knob. The microtubules are also in a constant state of flux, with units of tubulin protein continually polymerising and depolymerising in response to changes in the biochemical environment of the cell. Maintaining quantum coherence along and between these busy structures would be the neurobiological equivalent of walking on waterbalancing a hundred teacups on your head whilst dancing the hokey-cokey.

The conscious field

There is however a perfectly good wave mechanical system in the brain: the electromagnetic field (em-field). All electrical phenomena involve the generation of electromagnetic fields. Neurones have massive voltage differences across their cell membrane (Figure 12.2) and voltage difference is of course a measure of the gradient of the em-field. But this field will extend into the space beyond the neurone. The fields generated by one hundred billion neurones will overlap and superimpose to generate an extraordinarily complex em-field within our brain.
And the dynamics of electromagnetic fields is always wave mechanical. Light waves are an oscillation of the electromagnetic field and display all the quantum mechanical phenomena of interference (the two slit experiment), superpositions (the polaroid lens experiment), and uncertainty at any temperature. It is only matter, made up of atoms and molecules, that generally hides its waviness under a cloak of decoherence at normal temperatures.
The philosopher, Karl Popper, proposed in 1993 that consciousness was a manifestation of some kind of force field in the brain and the idea was further developed and extended by Lindahl and Århem (1994). Popper pointed out that many of the properties of mind were also properties of forces (mind is incorporeal yet capable of being influenced by matter and also capable of influencing matter - so are forces). He proposed that the mind is a three layered structure. The neurones with their action potentials represent the bottom layer that interact directly with the body. The next layer, the "electromagnetic wave fields (produced by neural activities)…. represent the unconscious part of our mind". This unconscious field would interact with neuronal activity via the forces it generates. Lastly, the "conscious mind - our conscious mental intensities, our conscious experiences - are capable of interacting with these unconscious physical force fields" (Figure 12.4).
Popper's suggestion of mind as a wave phenomenon has a lot of resonance with, at least my own, subjective experience of consciousness. The representation of thoughts and ideas as waves that ebb and flow throughout the brain seems to describe my state of consciousness far better than any neuronal firing model. However, Popper's proposal still leaves our conscious mind somewhere out there - in the third layer - not really part of the physical brain but communicating with it via the (unconscious) em-field. What this conscious layer is made up of, and how it communicates with the unconscious em-field, is left undefined.
The neurobiologist Benjamin Libet (who performed the neuronal initiation experiments that I described above) proposed an alternative field theory of mind with two, rather than Popper's three layers (Figure 12.4). The brain with its action potentials still represent the bottom layer but above this is the conscious mental field (CMF) that generates ".. a unified or unitary subjective experience". The CMF would have a "causal ability to affect or alter neuronal function" and thereby provides the veto or reinforcing role on unconsciously initiated actions, that Libet proposed for his volition experiment. Libet's CMF is more economical than Popper's model (having only two rather than three layers); but its nature remains mysterious. Libet states that the CMF "would not be a category of known physical fields, such as electromagnetic, gravitational, etc. The conscious mental field would be in a phenomenologically independent category; it is not describable in terms of any externally observable physical events or any known physical theory as presently constituted." However, a field that is affected by the electrical activity in the brain and is in turn able to modify that electrical activity seems to me to be virtually indistinguishable from the conventional electromagnetic field of the brain. Rigorous application of Occam's razor would leave just a single entity: the conscious electromagnetic field or the Cem-field.
All electrical activity induces an em-field (as in a radio transmitter) and the induced field modifies that electrical activity (as in a radio receiver). Neuronal electrical activity in the brain will induce an em-field and that field must in turn modify neural electrical activity (whether it causes changes in firing patterns is a more difficult question that I will be returning to). It therefore makes much more physical sense to me, to simply equate the conscious mental field with the induced em-field of the brain: the Cem-field (Figure 12.4).
It may seem peculiar to ascribe the reality of our thoughts to something as ephemeral as an electromagnetic field, but it isn't. We tend to be impressed with matter as representing the ultimate corporeal reality but it is in fact no more real than radiation. Einstein's famous equation (E = mc2) tells us that matter and energy are two manifestations of the same thing: a kind of matter-energy. Indeed, our exploration of the source of motion in Chapter 6, demonstrated that all the interactions that we see between objects around us (such as the kicking of a football) are really conducted through em-field's. It is the electromagnetic field of our boot, rather than the boot itself that moves the football. So why can't the thought, kick, be an em-field within our brain, which initiates the neuronal firing that leads to that kick?
The concept of information encoded within em-fields is also very familiar to us. Most of my thoughts seem to be composed of words and images, but this kind of visual and auditory information is routinely transmitted through space to our TV screens by em-fields. When our TV receiver picks up the waves, they are converted to electrical activity to make sound and the pictures on the screen. Similarly, our brain may be the receiver that picks up the auditory and visual information, held within the em-field of our conscious thoughts. When we think, 'rock', the concept rock may be held in our brain - not as a specific pattern of neuronal firing - but as a complex em wave induced by the firing of many neurones concerned with its colour, shape, texture etc. Each neurone contributing to the thought will generate its own em-field but these fields will superimpose - with appropriate reinforcements and interferences - to form the complex wave that corresponds to 'rock' inside our mind.
But is there any evidence for this? It may all sound a bit far fetched but it requires just three propositions to be true. The first is that our brain generates an em-field that encompasses a significant fraction of its neurones. The second is that our consciousness is a product of the em-field generated by our brain. The third is that the conscious em-field of the brain influences neuronal firing. If each of these propositions is shown to be true then a conscious em-field is inevitable. Fortunately, they are all testable.

Brain waves

The existence of an em-field associated with the brain was known as far back as 1875 when the English physiologist Richard Canton made electrical recordings from the surface of the brains of dogs and rabbits. Today, electroencephalogram (EEG) monitoring is routinely performed on human subjects by harmlessly placing electrodes on the surface of the subjects skin, above the skull, to record em waves generated by electrical activity in the outer surface (the cerebral cortex) of the brain. The characteristic rhythms (alpha, beta, theta and delta) vary according the subjects state of alertness, yet their source is still somewhat mysterious. We know that the firing of individual neurones cannot be generating them. The signal from any single neurone would be far too weak to be detected. The waves must instead be a manifestation of the synchronous firing of many thousands of neurones from different regions of the cerebral cortex.
It is unlikely that the physical reality of our consciousness could be the em-field that encompasses the whole brain. Patients who have had to have big chunks of their cortex destroyed often remain fully conscious. Most famous was the case of Mr Phineas Gage who in 1848 was the foreman of a railway construction gang in New England, when an accidental explosion shot an iron bar (3 feet long and more than an inch thick) through his left eye socket up into his frontal lobes, and out through the top of his skull. The bar took with it a big chunk of the frontal lobe of Mr Gage's brain, yet he remained conscious and even recovered well enough to return to work some 7 months later. He did not however retain his job as his personality had drastically changed. A physician named Harlow described Mr Gage as "fitful, irreverent, indulging in the grossest profanity." But he also noted that "The now extremely rude Phineas Gage is an object of immense medical interest, for it seems clear, from his somewhat crude experience of psychosurgery, that one can alter the social behaviour of the human animal by physically interfering with the frontal lobes of the brain." Mr Gage died fifteen years later but Dr Harlow's observation became one of the inspirations that led to the infamous and now discredited practice of performing frontal lobotomies on psychiatric patients .
So we cannot equate consciousness with any kind of field that overarches the entire brain. Instead the em-field of consciousness is likely to be much more localised within our brain, encompassing many millions of neurones within the cerebral cortex and thalamus regions, but its precise location may shift and change in response to changing neuronal activity. Scanning techniques such as electroencephalogram (EEG) or magnetoencephalogram (MEG) are used to detect these shifts and changes in the brain's em-field. Event-related potentials (ERPs) of the order of tens of volts per metre (voltage is a measure of the gradient of the electric field) are generated in response to a variety of auditory, visual and tactile stimuli .
The brain's conscious em-field It must also be relatively robust since it should not be significantly affected by the electromagnetic fields that we encounter in our daily lives (although whether we could know that our thoughts were being modified by external fields is a difficult question: whose mind would know?). However, this is not such a problem as it may at first appear. Movement of electrical charges in the head neutralises external electric fields to form what is known as a 'Faraday cage' that protects the brain from most of the electrical fields that we are likely to meet. We are however relatively transparent to magnetic fields and patients undergoing magnetic resonance imaging (MRI) scanning are routinely exposed to very strong magnetic fields. The MRI field will inevitably remodel the magnetic component of the (proposed) conscious em field in the brains of patients undergoing scanning. Yet there is no evidence that MRI scanning causes any significant changes to our thoughts or actions (none at least that can be distinguished from those provoked by load banging generated by the electric coils). However for any modulation of the cem field to have an observable effect, it must modify nerve-firing patterns. The static magnetic fields employed in MRI scanning, couple only very weakly to tissue and are unlikely to significantly affect neurones. Changing magnetic fields couple more strongly to tissue by inducing electrical fields that may stimulate neurone firing. And there is abundant evidence (see below) that rapidly changing magnetic fields do indeed affect brain activity.
The recently developed technique of magnetoencephalography (MEG) uses a superconducting quantum interference device (SQUID - we have already met this device in Chapter 9, it is used as an exquisitely sensitive em field detector), to generate a map of the brain's own em field. If the Cem field theory is correct, then somewhere within those MEG maps lies the (shifting) seat of consciousness.

Dancing to the same fiddle

The second proposition, that our conscious mind is a component of the em-field is far trickier to prove, particularly as nobody can agree on what consciousness actually is in the first place. Libet has proposed a curious test of his CMF theory of human consciousness that could work equally well for the Cem-field theory. It would however involve some rather tricky neurosurgery. Libet suggested that during therapeutic excision of a portion of the cortex, a slab of cortex tissue be kept alive for experimentation. The excised brain tissue would be placed back in situ within the brain but with all its neuronal connections severed. If fields are involved in consciousness, then the field from the excised tissue may still be able to interact with the field of healthy tissue and thereby impact on the subject's conscious experience. If, for instance, the excised tissue was from the visual cortex, then electrical stimulation of the excised tissue may cause the subject to see lights despite the fact that he is no longer hard-wired to the bit of his brain that is being stimulated!
Whether such an experiment would be practically (or ethically) feasible is a question I happily leave to neurosurgeons. But there may be easier ways to test whether the physical basis of consciousness is the Cem field. A prediction of the theory is that conscious awareness should correlate with changes to the Cem field. The simplest way for neuronal activity to impact on the em-field is for lots of neurones to fire; and there is abundant evidence that this is indeed a factor in conscious awareness. However, this in itself does not distinguish between a neuronal and a field theory of consciousness. But recall that a field is made up of waves that have all the interference effects we discussed in the earlier chapters. If lots of neurones fired randomly then the peaks and troughs of their individual EM waves would not coincide but interfere to generate a zero net field (or, to put it another way: the waves would decohere). For neuronal firing to have a big impact on the conscious field, neurones must fire in synchrony - they must dance to the same fiddle - so that the peaks and troughs of their em-fields will march in step and reinforce one another.
Reinhard Eckhorn and his colleagues at Philipps University in Marburg, Germany and Wolf Singer and colleagues at Max Plank Institute for Brain Research in Frankfurt, discovered that when animals perceived visual stimuli, local and distant clusters of neurones in their visual cortex fired in synchrony to generate coherent 40-80 Hertz (oscillations per second) brain waves . The researchers Eckhorn and others went on to suggest that these 40-80 Hertz oscillations link distant neurones involved in different aspects (colour, shape, movement, etc.) of the same visual perceptions and thereby could bind together features of a sensory stimulus by generating synchrony between discrete cortical areas. Wolf Singer's group and colleagues at the Max Planck Institute for Brain Research in Frankfurt also monitored the firing of small groups of neurones in the visual cortex. They discovered that when cats were shown two independent images of a bar moving in different directions on a screen, then individual neurones that responded to each image would fire at different times, asynchronously. However, when those same bars moved together on the screen (as a single bar), then the nerve cells fired in synchrony. It appeared that the cats registered each bar, as a single pattern of neuronal firing but their awareness that the bars represent two aspects of the same object, was encoded by synchrony of firing.
Even more startling were experiments performed by using an arrangement of mirrors to present a different moving image to each eye. The experimenters monitored the cat's eye movements to determine which image it perceived (the assumption being that its eye would follow the image that its attention was focused on). When only one image was presented then only that image was perceived. However, by presenting a rival image to the other eye the experimenters could interfere (perhaps wave interference?) with the perception of the first image and capture awareness. Remarkably, awareness of an image did not generate any change in the number or frequency of neuronal firing events in the visual cortex, but it did change their synchrony. When the cats focussed upon a particular image, then those neurones that saw that image fired in synchrony. When awareness was lost then those same neurones still fired, but randomly. Once again, awareness correlated, not with a pattern of neuronal firing, but with synchrony of firing .
If synchrony is important for awareness then we would expect that disrupting synchrony would disrupt awareness. Gilles Laurent and colleagues at the California Institute of Technology in Pasadena examined this question in insects. Locusts have about 1,000 neurones in the antennal lobe of their brain, which is involved in their sense of smell. When the insects sniff a particular odour then about 100 of these neurones fire. However, it was not just the pattern of neurones that seemed to carry information about odour but the synchrony between individual neuronal firings. Laurent's group also discovered that a neurotoxin called picrotoxin abolished the synchrony of firing. They were then in a position to address the issue of whether synchronous firing actually means anything to the insects. For this purpose they switched to honeybees since they can be trained! Rather like Pavlov's dogs, honeybees can be conditioned to stick out their tongue to obtain a reward when they smell a particular odour. However, when the bees were treated with picrotoxin, they lost the ability to discriminate between similar scents. Awareness of the difference between these scents appeared to be encoded in synchronous firing of their neurones.
Examining the role that synchronous firing plays in perception in the human brain is much more difficult since we cannot easily monitor the firing of individual neurones. There is however abundant evidence from EEG and MEG (magnetoencephalography) studies that synchronous firing in different regions of the cortex (to generate an EEG wave) correlates with awareness and attention. Experiments from the Laboratoire de Neurosciences Cognitives et Imagerie Cérébrale in Paris and the Institute of Psychology in Jena, Germany, demonstrated synchronous firing in distinct regions of the brain when a subject's attention is aroused . In the Paris experiments, subjects were shown black and white patterns that vaguely resembled a human face. When the subjects saw nothing but patterns of black and white (they did not recognise the image as a face) then their neurones fired but asynchronously. But when the subjects recognised that they were looking at an image of a human face then their neurones snapped into phase and fired synchronously. In the German experiments the subjects were shown a visual stimulus - a red or green light - that was accompanied by a small (relatively painless!) electric shock to one of their fingers. Subjects soon learnt to associate the coloured light with an expectation of receiving a shock and this associative learning was accompanied by synchronous firing in the regions of the cortex involved in the visual stimulus together with the cortical area representing the hand that had received the stimulus.
There is also circumstantial evidence that some anaesthetics disrupt synchronous firing and the state of anaesthesia is certainly associated with a lack of awareness in humans. Indeed, signs of wakefulness (movement, eye opening) in women undergoing general anaesthesia for caesarean section, were found to be associated with restoration of 30-40 Hertz oscillations in brain activity. Morphine has also been found to disrupt synchronous firing of neurones in rat brain, indicating that morphine-induced hallucinations in humans are probably also associated with disruption to synchronous firing .
How does the brain use synchrony? How does it even detect it? Many neurophysiologists consider synchrony to be an epiphenomenon (a by-product of a process, not relevant to its mechanism - like the whistle of a steam train); whilst others, like Eckhorn, believe that the brain uses these phase-locked oscillations to tie together separately processed features into a single perceived object. However, it is still unclear how the brain uses synchronous firing to tie perception together. What part of the brain oversees these distant firings? The simplest explanation seems to me to be that synchronous firing generates coherent disturbances to the Cem-field and thereby impacts on our consciousness (I have no problem with the concept that a bee or indeed any sentient animal has some degree of consciousness. Until we know how consciousness is encoded then I don't see how we can exclude it from any animal).
The Cem field theory of consciousness would also predict that stimuli that do not reach our consciousness should not disturb the Cem field. This can be tested during habituation, the phenomenon that we no longer notice a particular stimulus (for instance, the ticking of a clock) when that stimulus is monotonously repeated. Although we can't examine the Cem field directly (since we don't yet know where the Cem field is localised in the brain or even if it is localised), there is abundant evidence that habituation in animals and man is accompanied by a reduction in the magnitude of perturbations to the brain's overall electromagnetic field. There have been numerous experiments in man and animals that have demonstrated habituation in EEG patterns: the subject EEG response to a stimulus, such as a loud noise, diminishes when that stimulus is repeated . EEG measures the component of the brain's em field outside the head but magnetoencephalography (MEG) can directly measure the brain's em field within brain tissue. MEG detects perturbations to the brain's em field when a subject perceives a visual or auditory stimulus and studies have demonstrated that the amplitude of these perturbations diminishes upon habituation.
So there is abundant evidence that the changes to the brain's em field correlates with conscious awareness. This does not of course prove that these em field perturbations are our thoughts, but it is at least consistent with that hypothesis.
Waves move matter
The third and final proposition of the Cem field theory iswas that the Cem-field impacts on neuronal firing and thereby wills our actions. Em fields routinely modify electric currents in our radio and TV receivers; but can they similarly modify the electric currents in our brain? As I have described above, neuronal firing is normally triggered by the opening of voltage-gated ion channels (Figure 12.3). Voltage is a measure of the difference between the electromagnetic field at two points in space so voltage-gated channels are sensitive to the brain's em field.
Voltage-gated ion channels see the em field because they possess charged amino acids that move in the field. The channels are composed of a ring of proteins surrounding a pore in the cell membrane that allows ions in and out. Each protein consists of a string of amino acids that loop in and out of the membrane. One of the loops (called the S4 segment) contains a stretch of positively charged amino acids that seems to act as a kind of lid on the pore. As we discovered in Chapter 6, charges experience a force in an em-field, so the charged protein lid will respond to changes in the em-field by moving to a position in the field where their potential energy is at a minimum. This motion (or action) is thought to be responsible for opening or closing of the pore.
The em-field in the membrane of the neurone will be modified by the global em-field. There is therefore the potential for the brain's em field to modify neuronal firing patterns. However, recall that the voltage difference across the cell membrane is very massive (thousands of volts per centimetre). The voltage drop that triggers neuronal firing (from -65 to -40 millivolts) represents a shift of about 5,000 volts per centimetre - a very steep modulation of the em-field across the membrane. The gradients of the global em-field are far smaller than this, so on its own, the global em field would be insufficient to trigger neuronal firing from a resting state. However, neurophysiologists have long known that neurones exhibit a considerable range of excitability (epileptic seizures occur when neurones become uncontrollably excited). So amongst the electronic network of 100 billion neurones in our brain, there will be very many neurones fluctuating around the threshold potential necessary for firing. These undecided neurones will be very sensitive to the brain's em-field. Sometimes the em-field will reinforce the voltage difference across the cell membrane to stimulate neuronal firing; on other occasions, the em-field will diminish the voltage difference to suppress firing.
It is difficult to prove that the brain's own em field modifies neuronal firing but there is abundant evidence that relatively weak external electromagnetic fieldswaves can impact on neuronal activity. Slices of guinea pig and turtle brain have been shown to respond to external em fields as low as a few volts per metre . Isolated neurons can also respond to weak electric and magnetic fields . The evoked potentials detected generated in living brains by sensory stimuli are usually stronger than the relatively weak fields used in these experiments. If neuronal firing patterns are modified by external fields then they are surely also modulated by the brain's own fields.
External fields have also been shown to effect brain activity in whole animals and man. Henry Lai and colleagues at the University of Washington demonstrated that rats exposed to microwave frequency radiation were less able to find their way through a maze . Work by C.K. Chou and Arthur Guy of the Neuroscience Medical Center in Seattle has demonstrated that microwave radiation can induce sensory auditory responses in rats and guinea-pigs (the animals hear the field); and many studies have found that exposure to em-fields can cause changes to patterns of neurotransmitter release in experimental animals. There have been a number of studies in human volunteers that have demonstrated that electromagnetic fields produce changes in EEG profiles, particularly during sleep; and very many (often poorly controlled) studies on the effect of mobile phones or overhead electrical cables, on human health. There have also been many studies on the effect of mobile phones or overhead electrical cables, on human health and cognitive skills, though often with conflicting results . A recent trial performed by Dr Alan Preece of the University of Bristol discovered that subjects subjected to mobile phone frequency microwave radiation had quicker response time than control subjects. The strength of the induced em fields in the brain of subjects exposed to external sources of electromagnetic radiation is usually much lower than the fields generated by the brain's own activity . Electromagnetic fields have even been used therapeutically. Transcranial magnetic stimulation of the brain by electrical coils placed on the scalp generates induced electric fields that excite cortical neurones and has been used to treat psychiatric disorders such as depression . There is no evidence that MRI is in any way detrimental to health but rapidly changing magnetic fields are avoided in MRI scanning because they can induce nerve firing.
If external em-fields can perturb neuronal firing in our brain then it seems reasonable to conclude that the brain's own em-field may similarly modulate neuronal firing. The Cem-field generated by neuronal activity will loop back to influence neuronal firing and thereby be capable of consciously willing our actions. This feedback loop will provide the kind of self-referral that many cognitive scientists and philosophers believe to be crucial to consciousness.
A conscious computer?
With our Cem field theory of consciousness in place, we will make some further modifications to our Gold Digger Mark II robot to give him a semblance of Cem field consciousness. The first ingredient is already there: the em-field of his brain circuitry. If this em-field overarched the entire circuitry of his brain (whether a parallel computer or a neural net) then the field would integrate information from all of the calculations being performed by all of his logic gates. The em-field would then have some characteristics of consciousness: we could hypothesise that the field would be aware of the (neuronal) electrical activity that generated it. However, and most importantly, there would be no way to test this hypothesis since his em-field, as it stands, would be impotent and dumb. There is no way that such a field could report its state to us. Gold Digger couldn't tell us whether he was conscious or not.
To have a voice, Gold Digger's em-field must be more than aware: it must communicate. We could engineer a communication channel for Gold Digger's em-field by copying our own brain's architecture and installing some em-sensitive logic gates. The computational processes would then loop back upon itself, through the electromagnetic field and the em-sensitive logic gates, to influence its own computation process and generate an em-field-sensitive output. The em-field-sensitive circuitry could drive a voice synthesiser to give Gold Digger Mark III's em field an audible voice. We could program Gold Digger to speak whenever his electromagnetic field contained visual information corresponding to an image of the Klondike (from his video camera) together with howling winds (from the microphone) and to say, "I see a mountain and it is cold and windy". The electrical activity that generated speech would in turn feedback into the em-field so that Gold Digger's em-field would become em-field aware of his action of speaking. We could program him to report on this awareness (whenever the electrical activity corresponding to initiating the actions of speaking became components of his Cem field) by saying, "I am aware that I have spoken of the Klondike". And who could say he was lying?
With even more sophisticated programming we could engineer Gold Digger to perform a continuous analysis of the contents of his em-field (generated by both his sensory input and motor outputs) and describe them to us in a stream of consciousness report of his mental state. Unlike his predecessor, Gold Digger Mark III would be instantaneously aware of all his sensory information as a single Cem field. It might also be useful to integrate his em-field-sensitive circuitry with the em-insensitive classical computational process so that the robot worked two levels. The first would be an unconscious serial or classically parallel computation that could perform routine tasks (general electrical and mechanical maintenance) as well as driving the walking machinery and maintaining his balance - tasks that were best handled by classical computational number crunching. The second level would be his em-field sensitive circuitry that would receive all the same sensory input as the unconscious part of Gold Digger's brain, but would function on a wave-mechanical level. These circuits would drive Gold Digger's voice synthesiser but would also have the ability to interrupt some of the lower computations to make him stop, start or change his direction of walking. We could engineer this high level override to take over Gold Digger's motor actions whenever a certain combinations of input (image of the Klondike plus howling wind) entered Gold Digger's em-field. Gold Digger would be aware of these voluntary actions since they would instantly feedback into his own em-field.
It is of course unreasonable to propose that Gold Digger, constructed with present-day computing technology, would have anything other than a very rudimentary kind of consciousness. His em-field could certainly not compete in complexity with the Cem-field generated by a significant portion of the 1011 neurones in our brain. But I believe a computer brain constructed with this em-field-feedback-loop would possess something indistinguishable from a primitive form of consciousness, perhaps equivalent to that experienced by animals with simple nervous systems.
Imagine now a biological version of Gold Digger's brain (switching now back to neuronal circuitry) in a primitive animal. Since the brain's em-field modifies neuronal firing it must affect some aspects of the animal's behaviour. The em field will inevitably become subject to natural selection. The ability of the field to instantly process information from millions of spatially separated neurones would surely be harnessed by evolution. Over millions of years, natural selection will inevitably modify the organisation and dynamics of the brain's em-field and optimise its interaction with the neuronal network. Conversely, other neuronal circuits that needed to be insensitive to the vagaries of the em-field (for instance, those controlling general locomotion or body temperature) would be insulated to protect their computations from the em-field. The animal's brain would diverge into a robust unconscious number-crunching neuronal network that would take over all the automated tasks of the brain and a conscious wave-mechanical system that performed voluntary actions. In short, the system would evolve into conscious minds.
This Cem-field theory of consciousness gives a physical reality to that most powerful perception of dualism within our own minds. The reason why it feels like our conscious mind takes over when we are driving and spot a hazard sign, is that our conscious mind does take over. It is at these points that the conscious em-field - which is able to integrate complex information much more rapidly than the neuronal number crunching network - overrides the neuronal circuitry to initiate voluntary actions. The Cem-field theory of consciousness thereby restores a measure of dualism to our mind; but it is a dualism rooted in physical reality. One part of our mind - the unconscious part - is matter-based; the other part - our conscious minds - is an energy field. Both aspects of our minds are equally real; they just have different physical manifestations.
But, you might say, the neurones involved in unconscious brain activity must also have an em-field. Why aren't these fields also conscious? Indeed why isn't my television set, which also generates an em-field, conscious? The somewhat surprising answer is that we have no way of knowing whether or not any of these fields are indeed conscious. The only conscious minds that can report to us that they are conscious are those that can communicate information about their conscious state. That information could be in the form of speech or sign language or a visual display on a VDU screen, it could even be encoded in the generation of a particular odour (remembering the author Samuel Beckett's corruption of the Cartesian maxim 'I stink therefore I am'). But for it to be demonstrably conscious it must communicate!
There is evidence that in some circumstances, parts of our brain may be conscious, but are unable, or have only very limited abilities to communicate. Roger Sperry and Ronald Meyers discovered the phenomenon of the "split brain" in experiments on laboratory animals in the late 1950's. In the 1960's patients who suffered from severe epilepsy that did not respond to conventional treatments were subjected to a drastic therapeutic remedy: cutting the corpus callosum in their brain. The corpus callosum is a bundle of nerve fibres that connects the left and right hemispheres of the brain and communicates information between these hemispheres. You may know that, with a few exceptions, the left and right hemispheres of the brain receive sensory information from, and control, the opposite halves of the body. For example, your left hemisphere controls the movement of your right hand; your right hemisphere receives sensory information from the left side of objects in your visual field. However the centre for speech interpretation and production in your brain is located in only one hemisphere: the left.
The split brain patients appeared perfectly normal and their seizures were gone. They could talk and read and seemed happy, alert and healthy. Yet Sperry discovered that they had a startling deficit. In one experiment, a word (for example "fork") was flashed so only the right hemisphere of a patient could receive the information. The patient would not be able to say what the word was. However, if the subject was asked to write what he saw, his left hand (controlled by his right hemisphere) would write the word "fork". If asked what he had written, the patient would have no idea. His talking (left-hemisphere mind) would be completely unaware of what his dumb (right hemisphere) mind was up to. He would know that he had written something, yet he could not tell observers what the word was. Similarly, if the patient was blindfolded and a familiar object, such as a toothbrush, was placed in his left hand, he appeared to know what it was - for example by making the gesture of brushing his teeth - yet he would be unable to name the object. But if the left hand passed the toothbrush to the right hand, the patient would immediately say "tooth brush".
Whether the right hemisphere of these patients was conscious - was aware of what it was doing - is impossible to say. Lacking the power of speech, the right hemisphere was unable to say whether or not it was conscious. The right hemisphere of the brain may on these grounds be considered an automaton or zombie brain but it could equally be considered to be a conscious but dumb mind. Similarly, there may be distinct em-fields in intact brains that are separated from the one that we - as speaking people - are aware of. The only conscious minds that we are able to listen to, are those that can talk.
So the conscious em-field must inevitable be located in those areas of the brain that influence motor neurone firing sufficiently to communicate: the motor, sensory and visual cortex together with the centres concerned with speech and the temporal lobes concerned with memory. People with intact brains will be conscious of the neural activities of both halves of their brain because these activities will be communicated to the speaking part through the corpus callosum. Once that link is severed, the right hemisphere is left dumb and its state of consciousness becomes a philosophical question. Similarly, whether other non-speaking regions of the brain are conscious or indeed whether any other em-fields are conscious are questions we cannot answer.
My strong suspicion is however that there is only one consciousness in our brains and inanimate electrical devices are not conscious. My reasoning is that I believe that consciousness is not just any old electromagnetic field. Just as not all matter is alive, not all em fields are conscious. Our conscious minds have been modified and improved been over millions of years of evolution to perform the function of conscious decision making. A dumb and impotent em-field would have no function and thereby could not have contributed to the fitness of its host. Without evolutionary development it would be left as a disorganised primordial field with only the faintest semblance of consciousness.

The great advantage of the Cem-field as a theory of consciousness is that it is simple and it makes testable predictions. It involves no new physics and no new biology. All that is required is a straightforward and indeed inevitable feedback loop between the brain's neuronal network and the field generated by that network. The theory also has many interesting implications for our understanding of awareness, emotion, creativity and problem solving and consciousness in animals. There are also fascinating possibilities for building and using electronic devices that could interact directly with the Cem-field.
But we must return now to free our gold prospector from his predicament. He is still standing at the foot of the mountain with sensory data streaming into his brain neurones. His brain's neuronal network will be busy performing its classical algorithmic computations on the various possibilities for action; but meanwhile his Cem-field (his conscious mind) will also be receiving the same data, via the field induced by neuronal firing. In many cases, the stimulatory and inhibitory synaptic signals received by the decisive neurone will be sufficiently positive or negative to resolutely trigger or inhibit firing, irrespective of what the Cem-field is up to. In these circumstances the Cem-field will have no influence on the neuronal computations process and zombie-level decision-making will ensue. But in many other situations, the stimulatory and inhibitory inputs into the decision-making neurone(s) will not be decisive and the neurone(s) will be left poised on the brink of an action potential. In these cases the pushes and shoves from the Cem-field may be decisive and a conscious decision may be made. Under these circumstances, there will be only very small changes of energy involved in the interaction between the Cem-field and neurones and this consideration inevitably returns us to the central theme of this book: quantum mechanics.

Making a quantum decision

It is interesting that when even hard-nosed