The Mushroom and the Synapse

Now that I have acquainted the reader with the full spectrum of the psilocybin experience (and others like it), it is time for us to focus our attention upon psilocybin's physical modus operandi. If we can get to grips with how alkaloids like psilocybin work their spectacular effects upon the human psyche then we will be one step closer to a preliminary understanding of the nature of the conscious human mind and the underlying factors governing the switch from normal awareness to the mystical perception of an intelligent Other.

At this point, consciousness lies at the centre of our inquiry. All our paths of investigation lead directly to it. The psilocybin cultural history covered in the first few chapters of this book arose solely because of the radical change in consciousness induced by the mushroom in the Aztec and Mayan psyche. The pre-LSD events at Harvard were likewise spawned by the psilocybin-induced state of consciousness. Indeed, the whole 60's thing happened, in part, precisely because of the new ranges of conscious experience originally kick-started into existence by the mushroom. The growing second wave of psychedelic research has likewise appeared on account of the compelling nature of entheogen-inspired states of consciousness. One cannot escape the mystery of consciousness. Psilocybin simply highlights the boundless nature and mystical potential of the human mind lest we allow this fortunate state of affairs to pass us by.

As I pointed out at the very outset to this book, if we are interested in apprehending the ultimate nature of the reality process then it makes sense to home in on consciousness since consciousness represents the interface which links us to the 'world out there'. If we can understand what consciousness is, then we might also understand how consciousness is able to be transformed and whether such a transformation does indeed yield bona fide insights into the subtle nature of Nature. Nothing less than reality is up for grabs.

In the chapters that follow, I hope to develop a new non-technical and user-friendly theoretical framework with which we can explain consciousness, and in which we can properly place the entheogenic experience. Essentially this conceptual framework derives from Aldous Huxley's reasonable assertion that the psychedelic experience results from an influx of information not normally available to us - hence the 'doors of perception' being 'opened' after ingestion of substances like, in Huxley's case, mescaline. What I eventually hope to show is that consciousness itself is a form of information; that physical matter can be described in terms of information also; and that reality consists of an evolutionary flow of self-organising information, with human consciousness occupying a significant functional role in the entire process.

However, before we can explore the exciting insights that such an informational model of reality yields, we must start from the beginning, that is, we must look more closely at the obviously important physical relationship between psilocybin and the human brain. That might sound rather intimidating but, lets face it, getting to intimate grips with Nature in order to ascertain the meaning of life, consciousness and everything that really matters was never going to be a simple piece of cake. I assure you that its a deeply fascinating piece of cake though.In any serious attempt to elucidate the brain processes underlying the psychological effects of entheogenic agents, one must utilise whatever relevant scientific data is at hand. In our case this means neuropsychological data, of which much has become available since the 50's era when Huxley wrote Doors.

Neuropsychology is a modern scientific discipline based upon the study of the nervous system, which consists of the body's entire network of nerve cells. These nerve cells, or neurons as they are more formally known, allow us to sense, transmit, and process information. Whereas other cells in the body are designed to, say, form tissues and organs, neurons exist solely to transmit information in the form of discrete signals or impulses. We are able to see, touch, smell, hear, taste, feel and think because we possess a vast network of these neurons which, between them, manage to continually process and communicate information both about the external state of the world and the internal state of the body.

Of particular interest to neuropsychologists is the detailed study of the brain (one component of the nervous system) and the way in which the brain's particular neurons function in order to produce thinking and behaviour. Since psychoactive substances are known to effect the way brain neurons process information, neuropsychology has made some headway into understanding the chemistry of the brain and the actual way in which psychoactive substances work. Thus, we now know something about how common psychoactive substances like tea, coffee, nicotine and alcohol interact with the brain's neuronal architecture to cause their desired psychological effects of stimulation or stupor.

However, the study of psychoactive substances is far from being neuropsychology's key research area. Of perhaps most prominence is the study of the effects of brain trauma, a condition in which specific parts of the brain are known to be damaged. A brief look at the rationale governing this kind of research reveals that we can approach the phenomenon of the entheogenic experience in the same theoretical way.

For instance, medical patients with brain tumours and a corresponding psychological deficiency are, despite their misfortune, of great interest to neuropsychologists because a causal relationship can be ascertained between the area of the tumour and the particular psychological disturbance. This is equally true of brain-damaged victims of accidents, for where there is localised damage one invariably finds psychological disturbances of a definite kind.

As an example, damage to the area of the brain known as Broca's area will often lead to language problems associated with speech production. Patients of this type will have no difficulty in understanding speech but will have a noticeable difficulty in producing speech even to the point of being mute. The point of interest is that a specific area of the physical brain is damaged with an associated specific psychological disruption. Once the neuropsychologist has gathered a wealth of such examples then psychological functions like language (which is often affected after brain injury) can be divided into various sub-systems or 'modules' operating in different areas of the brain, each of which can be differentially disrupted.

The upshot of this methodological enterprise is that science is now able to speculate about normal brain function, and is able to link localised physical brain mechanisms with aspects of the mind. This is quite an achievement, resulting directly from the prevailing 'localisation' paradigm governing a major part of neuropsychology. It is therefore not unusual to come across references to the 'mapping' of the human brain, where different areas are associated with different psychological functions.

Bearing this in mind, it becomes clear that we ought to be able to approach the entheogenic experience in much the same way. That is, by looking at the specific changes to consciousness arising from the unusual presence of specific substances in the brain, we should then be able to theorise about how normal consciousness arises. In other words, just as we can analyse abnormal language production and then speculate about how the language system works in normal people, so too can we analyse altered states of consciousness and thence speculate about the nature of normal consciousness. At any rate, by examining chemical changes associated with changes in consciousness we ought definitely to come to some understanding as to the nature of mindstuff and the ways in which it is possible to modify it via chemistry. On the face of it at least, this area of study promises a wealth of relevant psychological data with which to understand the mind.

Despite this reasoning, science, as should be crystal clear by now, has unfortunately been all but barred from psychedelic investigation since the late 60's when psychedelics became illegalised. And yet enough information on the psychedelic experience has been generated with which to construct a user-friendly theory of consciousness. Most of this information I have outlined in previous chapters, in particular, information on the fundamental type of global change in consciousness caused by psilocybin. If we add to this the relevant information regarding the physical details of psilocybin, then we shall be able to combine the two and reach some sort of sound theoretical conclusion about the nature of consciousness. Regardless of any legal issues, this mode of enquiry promises to be most fruitful. In fact it is rather apt that a mysterious phenomenon like consciousness should require such radical means with which to pry open its nature.

As mentioned, the brain consists of individual information-processing nerve cells or neurons. It is estimated that the human brain contains some 13 or so billion of them. This is an astronomical amount, comparable to the vast number of stars in our galaxy. It is also more than twice the number of people alive on the planet. These 13 billion neurons are the essential 'wetware' of the brain and, massed together with other cells that provide support and energy, they form the spongy grey matter residing within our skulls.

Although the evidence is overwhelming, it still seems extraordinary that this immense interconnected wet mega-blob of porridge-like neuronal stuff is bound up with the elaborate properties of the human mind. Although one might have reservations in associating a soft wet blob with consciousness, the association is indisputable. Scramble someone's brain either through a severe blow to the head or through some other such trauma, and their consciousness similarly becomes scrambled. Or, electrically excite the brain of a patient undergoing brain surgery whilst they are only under the effects of a local anaesthetic, and it transpires that the electrical stimulation evokes definite experiences. And, of course, certain chemical substances introduced into the brain serve to alter consciousness.

Hence, it is overwhelmingly apparent that the human mind with all its attendant beliefs, ideas, neuroses, fears, hopes, goals, and aspirations is intimately bound up with the unsightly wet blob brain. Indeed, what distinguishes Homo sapiens from, say, our primate cousins, is the sheer size of our brains and the mental abilities that such a relatively big brain grants us; abilities like self-awareness, language, complex social behaviour, foresight, problem solving, metaphysical musing and so on. We are what we are by virtue of our evolved brains, the phenomenon of human consciousness being determined by this fortunate evolutionary cerebral turn of events.

So what is the neuron exactly and how does it come to be involved not only in your reading of these words, but in the psilocybin experience also? What is it exactly that these billions of units do?Structurally, the neuron has 4 main components; dendrites, the soma (no relation to Wasson's soma!) or cell body, the axon, and terminal fibres. This may sound somewhat complicated but the essential principles involved are easily understandable, and are essential knowledge to anyone interested in how their brains 'do their thing'.

Imagine a big tree suspended in mid-air. This tree has a dense network of roots which join on to a bulbous lower trunk. Above this fat lower trunk is a long thin upper trunk which ends with a wispy network of branches. In this picturesque analogy of the neuron (which will be worth bearing in mind for the discussions to come when we try to imagine psilocybin's journey within the brain) the roots of the tree are the dendrites, the lower bulbous trunk is the soma, the long upper trunk is the axon, and the topmost branches are the terminal fibres. This is the essential structure of the archetypal neuron with its four distinct components, and all of the brain's 13 billion neurons are basically made in this kind of way.

The dendrites are the root structures of the neuron which serve to receive information in the form of signals/impulses from other neurons. In the analogy, the root network of the suspended tree receives signals from the branches of other trees suspended below it. These neuronal signals travel to the soma (lower trunk) where they are integrated. The singular result of this integration is then passed on to the axon (upper trunk), which in turn passes on the information to the terminal fibres (branches).

Already we can see that neurons transmit informational impulses in an orderly well-defined manner, that is, informational signals progress or flow through the neuronal architecture in one direction only. But what exactly are these signals? What sort of information do these tree-like neurons process?

Since neurons are living tissue they operate by making use of their inherent electrochemical property, which is to say that their particular chemical molecular structure allows electrical potentials to be generated. The neuron has been constructed by Nature in such a way that it can either fire or not fire depending upon its input from other neurons. Firing here means that the neuron sends forth an electrochemical impulse (a rapidly travelling wave of electrical excitation) down its axon to its terminal fibres, at which point the impulse can be transmitted to other neurons.

This then is the sort of information that neurons process. The information they carry is embodied in the electrochemical activity of the neuron - its state of either firing or not firing, transmitting electrochemical impulses on to other neurons or not transmitting impulses. This is rather like the 'bit' components inside computers, which are binary devices which store information by being either on or off, active or inactive. Neurons thus appear to operate digitally.

Neurons can either fire or not fire, they cannot half-fire. There is no room for doubt or indecision, only a logically determined discrete firing or non-firing signal according to what other neurons in their vicinity are doing. The purpose of the soma is to integrate all the incoming signals from its dendrites (signals which come from other neurons) in such a way as to yield one subsequent impulse down its axon - or not, as the case may be. The concept of threshold is therefore crucial here. For simplicity's sake, if there are a certain number of impulses received by the soma from other neurons then the firing threshold will be met and an impulse will be passed on down the axon. Conversely if the particular threshold is not met then there will be no impulse sent down the axon.

Don't relax yet, for there is one more important fact to consider. Neurons can be excitatory or inhibitory. If the neuron is excitatory then if it fires, as its name suggests, its impulse will be one that tends to cause excitation in other neurons with which it connects. In other words its impulse will add to the chances of the next neuron in line firing as well. On the other hand, inhibitory neurons should they fire are such that they will decrease the chances of the next neuron in line firing.

To use the suspended tree analogy again, imagine that the roots receive 100 impulses from the nearby branches of other trees below. The majority of these impulses, lets say, are inhibitory - that is, their inherent message being conveyed to the tree is "do not fire an impulse". After these signals are processed or integrated by the lower trunk of the tree a resultant impulse is therefore not passed along to the upper trunk and branches, and thence no signal is conveyed to subsequent trees above.

And there you have it, the essential features of the brain's neuronal machinery in a highly sophisticated nut-shell. Information is transmitted and processed by the brain via the collective firing patterns of billions of neurons. Like the myriad on-off bit components of a computer, unbelievably large systems of neurons are able to carry out various computational processes and procedures, although in the case of the brain it's capacity to compute and literally think far outstrips the capacity of any currently existing computer. To imagine a sentient HAL-like computer by 2001 which worries about being turned off is, perhaps, excessive wishful thinking. Whilst computers might be good at numerical calculation and other well-defined logical operations, they fail miserably when it comes to carrying out the types of thinking which we do all the time like crossing a really busy whilst simultaneously contemplating a Shakespearean metaphor. Perhaps if computers were born into a society of computers, were able to form intricately detailed models of reality, and were able to continually re-write themselves, then maybe they might eventually come to possess mindful characteristics. As it stands, what partly determines human consciousness and the human self is the vast web of social and societal relations which impinge upon us, the complex internal models of reality which we build and store, and the continual learning processes we undertake (given its global connectivity, I concede that the internet might eventually achieve some sort of intelligence/sentience).

When considering the organised neuronal activity of the human brain, what we must actively strive to appreciate is the enormity of the system and the different patterns of impulse firing that the whole system can potentially embody. Not only are there billions of discrete neuronal firing devices, the amount of connectivity between them almost defies calculation. It has been estimated that each individual neuron can potentially pass on impulses to as many as 10,000 other neurons, and is in receipt of as many as 50,000 potential impulses from other neurons. In our tree analogy, each tree could therefore receive, integrate, and pass on impulses to and from vast forests of other trees.

Based upon the above figures it has been calculated that the informational storage capacity of the brain is comparable to the content of all the books ever written. It is this bewildering capacity to process and store information that makes the human mind as rich and as complex as it appears to be. Without the brain's ability to continually channel and organise billions of bits of information, the conscious human psyche as we know it could not exist.

This wealth of neuronal complexity which we all carry around in our 'big' heads is staggering to say the least. At any one moment the entire network can be in an essentially infinite amount of states of firing, and somewhere amongst such informational complexity lies our consciousness - who and what we are. Before dwelling upon this obviously compelling mystery, there is yet more relevant data to consider. According to the outline of neurons given thus far, it might be assumed that they contact one another directly. We might suppose that the terminal fibres of neurons pass on their firing impulses directly to the dendrites of other neurons. In the tree analogy this infers that the branch tips of one tree touch the roots of others. However, this is not the case. What is more, the actual mechanism in which neurons relay their electrochemically mediated information to one another is the very place where psychoactive substances like psilocybin and your morning cup of caffeine-enriched coffee are believed to operate. To be more precise, the synapse is where its all at.

The synapse is the junction between two neurons, the place where they communicate, and is arguably the most interesting feature of neuronal activity, for it operates with chemical substances which psychoactive drugs resemble. In fact, as we shall shortly see, all of the most powerful psychoactive drugs act by mimicking the brain's own chemical substances employed at synaptic sites.

The chemicals employed at the neuronal synapse are called neurotransmitters since they are the chemical agents which allow neurons to transmit their electrochemical impulses to one another. Instead of one neuron directly fusing onto another, there is an intervening gap between them - the synaptic cleft - over which impulses must be conveyed if they are to pass on their informational content. This synaptic gap is so small that it can only be discerned with the aid of the electron microscope. Yet despite its microscopic size, a tremendous amount of chemical activity can and does occur in the synaptic cleft so that, in reality, the microscopic gap is more of a busy molecular chasm.

Basically, when an electrochemical impulse reaches the synapses at the end regions of the neuron's terminal fibres (the tips of the branches in our tree analogy), it causes a neurotransmitter substance to be released into the synaptic cleft. After this substance has flooded this intervening space, some of its molecules bind themselves to special receptors on the surface of the dendrites of the receiving neuron. After the binding has occurred, the original impulse is re-generated in this neuron and subsequently passed on towards other neurons.

In order to fully appreciate the scope, scale, and intricacy of synaptic information transmission, permit me to employ another picturesque analogy. Instead of a terminal fibre/dendrite synapse, think of two train tunnels that do not meet but have an intervening space of, say, 10 metres between the ends of each of them. Furthermore, imagine that a train speeds along one of the tunnels at 100's of miles per hour. This is akin to the high velocity impulse travelling along a neuron. Not dogged by track problems, this 'Intercity Electrochemical Impulse Express' reaches the end of the tunnel and duly crashes onto specially constructed buffers. The dramatic impact upon the said buffers causes a group of strategically placed gas canisters to explode, thus dispersing their gaseous contents into the gap between the two tunnels. The gases instantaneously diffuse across the gap and cause a reaction to occur to a stationary train situated at the start of the next tunnel. As soon as molecules of the gas reach this next train, a neat reaction occurs in which the engine roars up and the train is off, at the same speed as the first train. Meanwhile the gas molecules in the gap are immediately 'mopped up' (and then conveniently re-cycled) so that they do not cause the replacement train (which magically appears almost instantly to replace the one that just sped off) to start up also. And in the first tunnel the original train has also been removed in order to allow another to follow if needs be.

Though elaborate, this analogy is nonetheless a relatively simple representation capturing the principles of the information communication which occurs at a single synapse. Although one might argue that a speeding train is a physical thing and an electrochemical impulse is not strictly a physical thing, the most important feature is the activity of the system and the informational state that it is in at any given moment. We could equally imagine a speeding band of fluorescent light or even a speeding vortex of turbulent air travelling down the tunnels; it does not matter. What really matters is the informational state of the components of the system - i.e. their relations with one another. In the actual neuronal synapse these crucial relations are defined by the chemical constituency of the whole system, that is, where and what effects various neurotransmitters are having upon the different parts of the synapse.

If the synapse is starting to sound ridiculously complex (as if Nature could not be that smart in her evolutionary manipulations), we should also keep in mind that the synaptic transmission of an impulse outlined above takes place in no more than 100 microseconds. In this outrageously short space of time, a few tens of thousand neurotransmitting molecules are released from the terminal fibres of one neuron, are diffused across the synaptic cleft, come to attach themselves to special receptors on the dendrite of the next neuron, cause an electrochemical impulse to be generated (or not), and are finally reabsorbed and recycled for further use by the first neuron. All this in 100 millionths of a second! Truly the mind boggles at the very processes underlying its boggling!

Despite the awesome intricacies of the neuronal system, I have deliberately ignored many of the other features to the neuronal transmission of information. For instance, the electrochemical impulse which shoots through the neuron is itself chock-a-block with chemical complexity. We find outrageously sophisticated potassium and sodium chemical pumps in the axon, we find vast oceans of charged particles or ions being continuously pumped in and out of the axon through special membrane channels so that an electric current is created, and we witness, finally, the aforementioned emergent wave of electrical activity whizzing along the axon to the terminal fibres and on to the synapses. That is the least that can be said to even begin appreciating the millennia-old work of environmental forces in shaping the evolution of the mammalian brain.

In general, a major conceptual flaw in our understanding of the workings of neurons is this distinct lack of appreciation for their relative size and speed of processing, an unfortunate fact which I am at pains to rectify here. Our modes of enquiry are such that we will tend to gloss over complexity. True, we don't have to marvel, gasp, and sit down in amazement at neuronal phenomena, yet to not do so (marvel at least) is to betray the subtlest fruits of the evolutionary process.

So, although we can examine individual neurons and ascertain the mechanism whereby they carry information and although we can recognise the role of neurotransmitting substances in propagating nerve signals from neuron to neuron via the synapse, traditional scientific approaches tend to fail dismally in fully conveying, in an emotional sense, the immense organisational complexity involved in the neuronal system as a whole.

Textbooks, for clarity, describe single neurons (as have I) and single synapses in a fairly cold and reductive manner. What seems never to be stressed is the magnitude of electrochemical changes which zip throughout the conscious brain. Literally billions of co-ordinated and meaningful molecular events occurring in literally billions of discrete locations at every moment virtually non-stop and somehow integrated so that organised sense results. This is seriously mean information processing with a vengeance.

If, then, we are attempting to marry such neuronal activity with psychological activity (i.e. consciousness), that is, if we are attempting to bridge the conceptual gap between mental and physical reality, then we must appreciate the organisational complexities involved. For if we merely skate over the immensity of these processes we shall be missing a kind of intuitive feel for the entire system.

Returning to the concept of organised patterns of neuronal firing, this becomes useful when we begin to think about the way the brain must work in everyday situations. If we take some important psychological function like, say, face recognition, then we can see that the particular pattern of neuronal firing caused by nerve impulses issuing from the visual system when it is looking at a face, will be, for any particular face, unique. In other words, each face we see will generate a unique pattern of neuronal firing - the face's neuronal signature - in our brain. Furthermore, the neuronal processing of faces would appear to reside in a specific area of the brain which can be selectively damaged resulting in prosopagnosia, a psychological disorder in which the sufferer fails to recognise faces, even those of close family members.

Similarly, we recognise different people's voices by virtue of the fact that each voice will cause a distinct pattern of neuronal firing which will be conducted from the auditory senses to deep within the brain. Eventually this pattern of information will reach that part of the brain where acoustical information is analysed and recognised. The same is true for different tastes. Each type of food or drink we consume will cause a different pattern of nerve impulses to be generated, which will finally reach that part of the brain which deals in the perception of taste.

In each of these cases, the neuronal pattern produced through the sensing of a particular face, voice, or taste will, at some stage, need to be compared with other possible neuronal patterns in order to yield its particular meaning and significance. Therefore, the different processing systems of the brain must act, in part, to provide a context for on-going neuronal patterns. Without such a contextual effect, neuronal patterns will not be able to yield their inherent informational content. The brain's capacity to provide a precise context for on-going neuronal patterns is thus crucial in understanding how neuronal activity and neuronal firing patterns can become meaningful.

The Berkeley psychology professor Bernard J.Baars has noted the importance of contextual effects in giving meaning to on-going neuronal patterns. He writes:

"We generally gain information about a world that is locally ambiguous, yet we usually experience a stable, coherent world. This suggests that before input becomes conscious, it interacts with numerous unconscious contextual influences to produce a single, coherent, conscious experience. Consciousness and context are twin issues, inseparable in the nature of things."

Although a detailed look at all the intricacies of neuronal firing patterns is beyond the scope of this book, for the time being it is enough that we grasp the essential principles which are likely to be involved in the brain's processing of information. Organised neuronal patterns arising from, say, visible external stimuli, contain a wealth of latent information about the stimuli, which is to say that the neuronal patterns are representations of those stimuli. The latent information in these neuronal representations then gets 'read' once the neuronal patterns are contextually processed. The brain, by supplying a context to neuronal representations, is able to access the meaning inherent in them.

One currently popular neurophilosophical approach to understanding mental states is that of functionalism, which, despite its dreary name, captures the important role of context in conscious brain processes. Essentially, functionalism views firing states of the brain as playing functional roles in an economy or language of such possible firing states, which is another way of describing the type of contextual effects outlined above. Any neuronal firing state of the brain derives its significance and meaning according to the functional role which it plays within a language of possible states. All possible states will be related to one another (just as words in the English language are all related to one another) and it is the network of relations (held within unconscious systems of the brain like the memory system) which act as context.

We now have at least a preliminary handle on the fundamental way in which the neuronal brain operates. Patterns of neuronal firing embody information and meaning which is read or accessed by the brain through language-like contextual/relational effects. Conscious experience would appear to be intimately bound up somewhere within this information processing system since it is consciousness which comes to experience meaning. We see faces and we know who they are. We see pictures and we see what they mean. We hear sounds and we know what they signify. Consciousness is therefore substantiated within neuronal information processing, and it begins to look as if consciousness were itself a form of information which emerges at the highest level of the neuronal system.

With these speculations in mind, let us look at the way in which psychoactive substances effect neurons, synapses, and, of course, consciousness. This is where physical processes can be seen to be connected directly to changes in consciousness, an area of analysis teeming with profound implications, especially when we consider the effects of psilocybin. More importantly, we might ascertain still more clearly how consciousness can be understood as a form of information.

There are drugs and there are drugs. To be precise, there are 5 principle classes of drugs which effect mood and behaviour, some of which we have already met and discussed. These are: depressants like alcohol, barbiturates, valium, and anaesthetics; stimulants like amphetamine (speed), cocaine, caffeine, and nicotine; opiates like opium, heroin, and morphine; antipsychotics like chlorpromazine (thorazine); and last but by absolutely no means least, there are psychedelics or entheogens like psilocybin, mescaline, LSD, and DMT. Also included as psychedelics are cannabis - since it can cause visual hallucinations at high doses - and the synthetic rave-drug Ecstasy (MDMA).

Despite the fact that the substances listed here as being psychedelic could be further divided according to the precise effect they have, this basic classification will suffice for the following discussion in which we will focus upon the way in which these substances are believed to work. Although we will briefly look at each class of substance, most attention will be paid to the known neurophysiological effects of psilocybin.

The predominant effect of depressants is to depress, or deaden, neuronal activity. Consider anaesthetics. They are so strong in their depressant action that beyond the state of general anaesthesia which they induce there lies only coma and death. It is believed that once anaesthetics have been administered, they reach the brain and inhibit neuronal firing so much so that consciousness is 'lost'. Therefore it is clear that without adequate neuronal firing there can be no information processing or informational conductance and hence no mindfulness. Already then, we have yet more proof that consciousness is bound up with the billionfold action of activated neurons in the brain.

If we take another depressant - alcohol - we find that it too acts to inhibit neuronal firing throughout the brain, and hence consciousness becomes depressed or reduced. However, at low doses the opposite effect pertains whereby there is a certain degree of psychological stimulation because of the initial depression of inhibitory synapses, which, as you will recall, serve to diminish neuronal firing. However, soon after these inhibitory neurons are depressed, excitatory neurons begin to be depressed as well and this effect comes to dominate the ensuing state of consciousness.

Not only do depressants act to inhibit neuronal firing in the brain, they appear to depress the activity of the body's other nerves, heart tissue, and muscle tissue. More specifically, depressants upset the functioning of the arousal centres in the brain such that psychological arousal and stimulation are diminished. In short, the quantity of consciousness is reduced due to a concurrent reduction in neuronal firing i.e. there is less informational patterning and less informational organisation happening within the neuronal systems of the brain once a depressant drug has become active.

Stimulants appear to have the opposite effect of depressants. Cocaine and amphetamine each work in virtually the same way, causing almost identical stimulatory effects such as euphoria, an increase in alertness, an elevation of mood, and a reduction in fatigue. Indeed, cocaine is derived from the coca plant, the leaves of which are still chewed daily by millions of South American native peoples precisely for the resultant psychological stimulation and reduction in perceived tiredness and hunger. This latter 'productive' effect of the coca leaf explains the fact that whilst the 16th century Spanish conquistadors outlawed the religious use of psychoactive mushrooms, peoples like the Incas were allowed to continue their practice of chewing coca leaves as long as it was whilst they slaved away in Spanish gold mines.

Amphetamine is believed to act in a way that mimics and increases the activity of the neurotransmitter noradrenaline (the brain uses many different types of neurotransmitter), thus interfering with the normal synaptic functioning of noradrenaline-containing neurons. This is because amphetamine is so similar in molecular structure to noradrenaline that it literally invades those neuronal areas where synaptic transmission with noradrenaline occurs and thence increases the rate of impulse generation. Once it has done so, the typical 'speeding' psychological responses take hold.

With cocaine a similar tale unfolds. In this case however, it appears that cocaine inhibits the re-cycling (the 'mopping up') of noradrenaline within the synapse after it has done its work. Because of this selective interference, there is more noradrenaline 'hanging around' in the synapse and therefore more of it to stimulate the receiving neuron into excitatory action.

In both cases, the chief physical effect is that of an increase in synaptic activity which causes stimulation of the nervous system. Again we see that the uplifting alteration in consciousness caused by these drugs is due to an increase in the information processing activity of certain types of neuron, in this case, neurons utilising noradrenaline. Increased neuronal activity of this kind then generates the desired psychological stimulation or 'high'. It is important to bear in mind here however, that the increased neuronal activity in this case does not lead to any kind of profound visionary experience. Such radical phenomenology is restricted to entheogens.

With good old tea and coffee, the active ingredient caffeine is believed to increase rates of cellular metabolism, thus making more energy available to cells. The net result of this action is once more an elevated rate of neuronal firing, which explains the subtle stimulatory properties of tea and coffee and their widespread use.

The third class of psychoactive substance on our list are the opiates which are derived from the natural opium poppy. The opiates are interesting for their variety of powerful effects. The world-wide painkiller morphine is an invaluable opiate and its chemical isolation from the opium poppy radically revolutionised medicine and the world-wide control of pain. Morphine seems to selectively bind to 'opiate receptors' in the brain, which suggests that the brain has its own pain control mechanisms. Indeed, it has been proposed that acupuncture and hypnosis might be able to reduce pain because they encourage the brain to generate it's own endorphins, which are opiate substances which will bind to opiate receptors (endorphins are also believed to be the cause of the high often felt after rigorous exercise). Once these opiate receptors are activated the emotional perception of pain diminishes - as opposed to a diminishing of the actual 'pain' impulses arriving from the site of injury. Along with opium and heroin (a semi-synthetic compound), morphine also generates euphoria and this is associated with the emotional changes wrought through the activation of the nervous system's opiate receptors.

With the fourth class of drugs, the antipsychotics, we find mass-synthesised compounds like chlorpromazine being used the world over to treat mental diseases like schizophrenia. Perhaps the most accepted neuropsychological theory holds it that schizophrenia results from an excess of the substance dopamine within the brain. As you might have guessed, dopamine is yet another of the brain's major neurotransmitters.

The excess dopamine explanation for schizophrenia is supported by the effects of chlorpromazine which diminishes the symptoms of this disease. Since chlorpromazine operates by blocking dopamine receptors in the brain, it is logical to assume that an excess of dopaminergic neuronal activity lies at the heart of schizophrenia. This leads to the intriguing conclusion that somehow an excess of dopamine-using neurons is intimately bound up with the strange delusions and belief systems of the unfortunate mind suffering from schizophrenia. By blocking the receptor sites of the excess dopamine, chlorpromazine therefore helps to block disorders of thought.

Here we have another strong clue on how to unravel the mysteries of the global formation and global emergence of consciousness, for schizophrenia is noted precisely for its global disruptions of consciousness. Furthermore, these vast disruptions in thought appear to be non-random in that certain definite types of delusion are observed, often related to feelings of paranoia and the belief that one is being controlled by horribly malevolent external forces. If dopaminergic synaptic overactivity really is to blame for these global thought disorders, then we can begin to conceive how large patterns of abnormal neuronal firing yield large disorders of thought i.e. delusions and the like. If neuronal activity becomes too overactive and too 'wild', then the resultant firing patterns might well be 'flawed', which is to say that such patterns are essentially mistakes serving to mislead the experiencer. Or, if there is some negative disruption to the overall way in which the schizophrenic conceives reality, then their model of reality will provide a faulty contextual effect upon on-going neuronal activity.

Obviously the human brain is a finely tuned information processing instrument. If the neuronal events substantiating some kinds of information processing are pushed too far from some criteria, or if neuronal events are 'read' by an erroneous contextual system, then faulty processing occurs with its resultant negative disruption of consciousness.

Finally we have come to the class of compounds we call the psychedelics or entheogens. Admittedly it has been a little tough getting here, yet the journey is worth it since the psilocybin mushroom is always worth pursuing for its striking implications relating to human consciousness. Thus, we are now ready to home in even closer to the link between neuronal chemistry and consciousness.

Psychedelic substances are by far the most interesting of all known psychoactive substances, although precious little is known about exactly how they are able to generate such a remarkable set of psychological effects. Psychedelics are often referred to by unwary clinicians as hallucinogens (as opposed to entheogens), yet this term suggests that hallucinations are formed. The general definition of an hallucination is that of a perceived object in 3-dimensional space which is in actuality not there - a bit like seeing a ghost or mirage. But this is not a typical effect of psychedelics as I hope I have shown in previous chapters. In fact, amongst the most prominent effects of substances like psilocybin is the induction of complex visionary scenes which unfold with closed eyes, along with the perceived increase in the 'realness' of the external world as viewed with eyes open. More specifically, one does not hallucinate non-existent objects, rather one comes to see external reality in a new and arguably enhanced way. It is for these reasons that the term entheogen or psychedelic (literally mind-manifesting) be preferred to classify these particular substances.

It is believed that psilocybin, LSD, and DMT work by mimicking the neurotransmitter serotonin (5-HT), one of the most important and widespread of the brain's synaptic neurochemical messengers. The mimicking occurs because LSD, and particularly psilocybin, possess an almost identical molecular structure to serotonin i.e. their shape is so similar that they are able to 'fool' and infiltrate parts of the brain which process information using serotonergic synapses.

Serotonin is employed in a number of brain structures which seem to control functions like sleep, mood, and general arousal. One of these structures is the raphe system at the base of the brain, whose serotonergic neuronal axons project to all other major areas of the brain, notably the limbic system (which controls emotional responses) and areas of the visual system.

According to noted neuroscientist G.K.Aghajanian, the serotonin-using raphe system has a homeostatic function in which two primary effects emerge. Firstly, in the waking state the system acts to enhance the activity of motor neurons which govern the control of muscular movement. Secondly, and more significantly, during the waking state this same serotonergic system acts to suppress sensory systems, which are those systems relaying information about the external world. This second effect, according to Aghajanian, serves to "screen out distracting sensory cues."

Furthermore, it has been speculated that this homeostatic 'screening out' function maintains a kind of 'balance' of consciousness in which we perceive reality in a 'steady' way, almost as if the serotonergic raphe system were a balancing stick enabling us to walk the 'tightrope' of normal perceptual awareness. If this serotonergic homeostatic balancing system is interfered with, then the perception of reality will be correspondingly altered, so much so that we may plunge off the tightrope into new dimensions of perceived reality. Chemically dismantling the raphe system's screening effect would therefore admit the entry of latent information into consciousness. Is this how agents like psilocybin work?

Most of the detailed physiological experimentation that was carried out with psychedelics in the 60's concentrated on LSD and psilocybin and used rat brains, cat brains, and isolated rat neurons. Perhaps the most important finding was indeed that LSD and psilocybin depress the action of serotonin neurons in precisely the raphe system (a neuronal system shared by rats, cats and humans). The usual activity of the particular serotonergic neurons which psilocybin and LSD depress is inhibitory which means that their normal firing serves to dampen or suppress activity in the those other parts of the brain with which they synapse. Thus it was believed that psilocybin and LSD's dampening effect on serotonergic neurons facilitated an increase in neuronal firing in those areas of the brain in contact with the raphe system (like the aforementioned visual and limbic/emotion systems). It was this effect, this enhancement of neuronal activation, that was believed to correlate with the entheogenic experience itself.

It seemed like a nice neat theory. However, things are never that simple when it comes to the actions of psychedelics. For the above scenario does not take into account the more recently discovered neuropharmacological action of mescaline, another classic entheogen. With not a little theoretical irritation we find that, like psilocybin, mescaline induces the full spectrum of visionary phenomenology but is not known to significantly effect the raphe system. Which means that our raphe theory is not the whole story. Just when it was all looking so clear....

Research over the last decade has revealed that there are distinct kinds of serotonin receptors, or serotonin binding sites, within the brain. In other words, neurons which are modulated by the release of serotonin from other neurons with which they synapse, are not tied down to just one kind of serotonin receptor. In typical fashion, Nature has made things more complex and intriguing than that. In fact, there appear to be many different kinds of serotonin receptor (called sub-type receptors) and it is believed that different psychedelic drugs have differential effects upon these receptors. One particular serotonin receptor though - the so-called 5-HT2 type - appears to represent a common site of action of both psilocybin and mescaline.

5-HT2 receptors are found throughout the cortex and also in abundance in the brain system known as the locus coeruleus which, like the raphe, is situated at the base of the brain. The locus coeruleus processes so many sensory inputs (a flow of incoming data if you like) that it is considered to function as a 'novelty detector' and is able to influence one's state of arousal. By monitoring the constant surge of 'electrochemical traffic' passing through it, the locus coeruleus is able to detect changes in the flow of data should a change occur and thus alert other parts of the brain. According to our expert G.K.Aghajanian, both psilocybin and mescaline bind to these 5-HT2 sites in the locus coeruleus and thus alter the functioning of this system, ultimately raising levels of alertness and arousal. In other words, it once again seems that entheogens function by making more information available to the experiencer.

We are now in a position in which we can summarise the above findings: the net result of psilocybin's combined effects upon the locus coeruleus and the raphe system is an increase in neuronal firing, a concurrent increase in consciousness (an increase in perceived reality), and the emergence of shamanic visions.

Of the above description, only the second claim is in any way contentious, for I suggest an increase in consciousness. Others might argue that the increase in neuronal firing in the brain is more of an unwelcome dysfunction than a constructive effect. However, such a negative judgement is to miss the implications of the entheogenic state of mind. After all, Huxley claimed that psychedelics could, through an act of 'gratuitous grace', permit one access to perceptual information that was 'out there', but not normally needed since from an evolutionary standpoint we need only information regarding things like food, safety, and sex. Or at least those are the sorts of thing it has been essential to know in our evolutionary past. Of course for Huxley and other champions of the psychedelic experience, the knowledge made available through visionary plant alkaloids was suddenly very important in the light of contemporary Western culture. A transcendental reality appeared to be awaiting us, ready to erupt amidst the mundane and oft-profane trudge of human history.

Armed with modern data on serotonin receptors and their infiltration by entheogens, we can see that Huxley was correct in his pioneering conjectures. Once entheogenic compounds have entered the brain, an increase in neuronal activity (i.e. an increase in neuronal excitation and electrochemical information processing) takes place - hence more information does indeed become accessible to the mind. In particular, the parts of the brain which become more activated are involved with novelty-detection, arousal, emotions, and the relaying of sensory information.

But what exactly does it mean that there is an increase in neuronal informational activity? Just how valid and 'real' are the novel patterns of neuronal firing orchestrated by psilocybin? Indeed, how can novel patterns of neuronal firing actually be conscious thoughts?

From here on the ground gets more uncertain, mainly because the brain is such an astonishingly complicated organ. However, before we go on to speculate and deal further with what has been said thus far, there is one more piece of information we should consider, namely the role of serotonergic neurons with the process of dreaming.

REM sleep, or rapid eye movement sleep, is that part of the sleep cycle in which we dream the most vividly. Sleep, let alone dreaming, is a peculiar thing, especially since we spend about a third of our lives succumbing to it. Despite such a dramatic nightly encumbrance, science has yet to reach a universally agreed reason why we sleep, for one can come up with plenty of arguments that counter explanations which view sleep as a purely restorative process. Proneness to attack comes to mind for instance, for when else are we so passively oblivious to our surroundings? As to why we dream, there are again numerous theories, from odd theories that we dream to forget, to theories that we dream to consolidate information.

Although we might not remember our dreams it is vital that we engage in REM/dream sleep each night. Sleep researchers have found that if periods of REM are selectively disrupted then this results in a rebound effect whereby the next night, barring any more selective interference from researchers, there will be an extra amount of REM, or dreaming. We absolutely must dream, and therefore dreaming has be related to some very important informational process of the brain.

Neuroscientist B.L.Jacobs has carried out experiments which show that a suppression of serotonergic neuronal activity elicits dreaming. If cats (unfortunately these most loveable creatures are often used for questionable brain-meddling sleep experiments) are injected with a chemical called PCPA which is known to block serotonin supplies to all parts of the brain, then the cats start to exhibit brain-wave patterns consistent with the onset of dreaming despite the fact that they are fully awake. In other words argues Jacobs, the cats are experiencing waking dreams.

Therefore, waking dreams are somehow associated with low levels of serotonin. Indeed, during dream sleep serotonergic cells in the raphe system will 'turn off' completely so that they cease having a depressant effect on other parts of the brain, a process which echoes the effects of psilocybin upon the raphe system.

The conclusion reached is that dreaming is associated with a form of neuronal firing normally kept at bay by inhibitory serotonergic neurons until the onset of sleep. More importantly, the visions produced by psychedelic agents like psilocybin might be the result of waking dreams. Or at least they might emerge from neuronal processes which are similar to those processes occurring whilst we dream. This idea is not only compelling, it also seems intuitively correct; the psilocybin mushroom allows one to experience dream-like consciousness whilst awake and these take the form of intensely moving visions behind closed eyes.

According to the various documented cases of the shamanic visionary state, entheogenic visions are indeed dreamlike, the only difference being that one is immeasurably more conscious during such visions than in dreams (even lucid ones) and one is able to remember them vividly, unlike dreams which appear to fade quickly. Whereas most people cannot, offhand, recall most of the thousands of dreams which they all must have had, psilocybin visions remain fairly emblazoned upon the memory, like favourite movie clips.

To be sure, the suggestion that psilocybin visions are dreamlike is theoretically useful, yet it seriously downplays their impact and dynamic vividness and 'Otherness'. But since there is clearly some similarity in the chemical basis and phenomenological quality of dreams with the chemical basis and phenomenological quality of entheogenic visionary episodes, their relationship - in terms of neuronal processes - demands further exploration, and so this is where we head, in part, in the next chapter. But, we must bear in mind that the vision-generating side of the mushroom experience is only the half of it, since the altered perception of reality with eyes open is of equal importance. However, as stated, both these phenomena are intimately related to the processing of information within the neuronal systems of the brain, and we therefore need to begin thinking more deeply about the relationship between billion-fold patterns of neuronal firing and consciousness. I have already introduced the idea that vast patterns of orchestrated neuronal firing are conscious experience, yet this concept is so much rife with profundity that I shall repeatedly return to it in order to fully explore its worth as an explanational model for understanding the nature of the brain/mind.

Whether it be a dream or an entheogenic vision, a normal perception of an object or a psychedelic perception, the underlying structure of such experiences can now be discerned. The common mediating factor is information, and the way in which such information is transmitted, organised, and substantiated within the neuronal firing of the brain. Information, the 'currency' of the brain, emerges as the key concept in explaining the normal conscious mind, the entheogenic mind, and the dreaming mind. We continue our numinous investigations in the next chapter, as we spiral in towards the secret of the shamanic earthly mushroom.