Simon Powell - The Psilocybin Solution

Here we have another strong clue about how to unravel the mysteries of the formation and emergence of complex consciousness—for schizophrenia is noted precisely for its disruptions of those higher levels of awareness that pertain to reality conception. Furthermore, these large-scale disruptions in thought appear to be nonrandom 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 disorders of thought, we can begin to conceive how large patterns of abnormal neuronal firing yield large disorders of cognition, such as paranoid 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 these patterns are essentially mistakes serving to mislead the experiencer. Or, if there is some negative disruption in the overall way in which the schizophrenic conceives reality, then the schizophrenic’s model of reality will provide a faulty contextual effect on ongoing 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, faulty processing occurs, with its resultant negative disruption of consciousness.

Finally we come to the class of compounds known as psychedelics or entheogens. Admittedly it has been a little tough getting here, yet the journey is worth it. We are now ready to home in even closer to the link between neuronal chemistry and consciousness. Entheogens 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 array of psychological effects. Entheogens are often referred to by unwary clinicians as hallucinogens, yet this term suggests that hallucinations are produced. The general definition of a hallucination is that of a perceived object in three-dimensional space that is in actuality not there—a bit like seeing a ghost or mirage. But this is not a typical effect, as I hope I have shown in previous chapters. In fact, one of the most prominent effects of substances like psilocybin is the production of complex visionary scenes that unfold behind closed eyes, along with a perceived increase in the realness of the external world as viewed with eyes open. More specifically, one does not hallucinate nonexistent objects; rather, one comes to see external reality in a new and more enhanced way. It is for these reasons that the term entheogen or psychedelic (literally mind-manifesting) is preferred to classify these particular substances.

It is believed that psilocybin works by mimicking the neurotransmitter serotonin (known as 5-HT), one of the most important and widespread of the brain’s synaptic messengers. The mimicking occurs because psilocin (the active metabolite of psilocybin that is formed in the body) possesses a molecular structure almost identical to serotonin. Psilocin’s shape is so similar to serotonin that it is able to infiltrate parts of the brain that process information using serotonergic synapses.

Serotonin is employed in a number of brain structures that 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.

Research indicates that the serotonin-using raphe system has a homeostatic, or balancing, function in which two primary effects emerge. First, in the waking state the system acts to enhance the activity of motor neurons, which govern the control of muscular movement. Second, and more significant, during the waking state this same serotonergic system acts to suppress sensory systems, which relay information about the external world. This second effect appears to screen out, or filter out, distracting sensory information. Furthermore, it has been speculated that this filtering mechanism allows us to 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 visionary agents like psilocybin work?

Most of the detailed physiological experimentation that was carried out with psychedelics in the 1960s 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 the raphe system (a neuronal system shared by rats, cats, and humans).

The usual activity of the particular serotonergic neurons that psilocin and LSD depress is inhibitory, which means that their normal firing serves to dampen or suppress activity in those 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 psychedelic experience itself.

It seemed like a nice, neat theory. However, the above scenario does not take into account the recently discovered neuropharmacological action of mescaline, another classic entheogen. With not a little irritation we find that, like psilocybin, mescaline induces the full spectrum of visionary phenomenology, but it is not known to significantly influence the raphe system. Therefore our raphe theory cannot be the whole story.

Research over the past decade has revealed that there are distinct kinds of serotonin receptors, or serotonin binding sites, within the brain. In other words, neurons that 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 are different kinds of serotonin receptor (classified by grouping them into subtype receptors), and it is believed that different psychedelic drugs have differential effects upon these receptors. One particular serotonin receptor, however—the so-called 5-HT2A type—appears to represent a common site of action for both psilocybin and mescaline.

The 5-HT2A 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 and alert other parts of the brain. When something changes in the environment around us, the locus coeruleus alerts the rest of the brain to the change. Both psilocin and mescaline bind to these 5-HT2A sites in the locus coeruleus and thereby alter the functioning of this system, ultimately raising levels of arousal. In other words, it once again seems that psychedelics function by making more information available to the experiencer.