There’s no doubt that the effect of psychedelics on the brain is one of the most interesting unexplained mysteries of neuroscience to date.
Psychedelic drugs have the ability to completely alter our state of consciousness and transform our sensory perception, which is curious considering the fact that we have not the slightest clue how sensory perception and consciousness is brought about from the signals of our brain, and yet some of the simplest compounds are able to completely drastically alter our mental state.
Within the realm of psychedelics, one particular psychedelic stands out as an incredibly powerful and interesting substance: N,N-Dimethyltryptamine, or DMT for short.
Whats so special about DMT?
Now you’re probably wondering what’s so crazy about DMT. Before we get into that, we should probably briefly cover the basics about the compound
DMT is a naturally occurring compound found in many plants and animals, and thus has been accessible to various groups all across the world for thousands of years.
Curiously, DMT is the only endogenous psychedelic, meaning that it is the only psychedelic that is found naturally within the human body.
Recent research has found trace amounts of DMT in the human pineal gland, and they’ve been able to identify the chemical pathway in the brain that produces this DMT, although it’s still a complete mystery why such a pathway even exists.
However, the most interesting and significant aspect of DMT is the type of experience it brings about when ingested.
People who take DMT routinely report an overwhelming experience where the entire world disappears before their eyes and is replaced with a completely different geometric reality. In this reality, people often report meeting with creatures that give them advice, and many describe the DMT experience as one of the most profound experiences of their lives.
Obviously, you may at first be very skeptical of this (and rightfully so). The thought that everyone is lying or misinterpreting their experience might come into your head, and you may be tempted to dismiss the substance as something for crazy people.
Hearing what some people who have taken DMT have to say might help to give you a sense for the profound nature of people’s experiences, and at least convince you that they are being genuine.
Also, to give you a sense of what the experience is like, you can watch the following video (I would recommend watching it in full screen, with your lights off and headphones for the best effect). Note that many people say that its not possible to properly capture anywhere close to the magnitude of the DMT experience in any explanation or video, but this video does give a point in the direction of what the experience is like.
At this point, you can probably tell that the DMT experience is an extremely unusual and powerful one that involves overwhelming feelings, complex psychedelic worlds, and mysterious creatures.
If you are still skeptical that DMT actually causes such experiences and they are legitimate (which is fine), then you may be interested in reading this post on the truth that lies in the seemingly irrational.
Otherwise, we can proceed with our exploration of DMT, trying to pick apart some of its effects and see if we can try to determine some neurobiological methods of action for the compound, or at least try to formulate a theory for its function.
An introduction to the theory we’re exploring
In this post, I want to highlight an extremely insightful overarching theory on the mechanisms of action of DMT that builds on much of the research on DMT thats been going on for the past few decades into one cohesive framework.
I’ll be going over the most important concepts of the paper, adding simplifications and my own comments, with the goal of explaining the theory on how DMT may work in the brain, why it’s able to create such complex and extraordinary changes in consciousness, and why it may exist in the brain.
If you want to read the full paper yourself (it’s 45 pages, but very well thought out/written and worth the read if you’re interested), you can find a copy here: Building Alien Worlds — The Neurophysiological and Evolutionary Implications of the Astonishing Psychoactive Effects of N,N-Dimethyltryptamine (DMT).
Keep in mind that this is by no means a definitive theory about the neurobiology of DMT, and there are certainly some holes in the theory (which I will try to point out as I go through), but it provides one of the most logically sound and thought-provoking frameworks on the topic that I’ve seen to date.
An important proposition about the nature of DMT
Before we dive into the technical details of the paper, it’s probably a good idea to first talk about what exactly the paper is trying to show.
When taking DMT, there is a notorious part of the experience a few seconds after ingesting the substance where the entire world disappears and you are chaotically transferred into a completely different state of consciousness.
This experience is often called breaking through and is also known as the DMT flash. We are going to try to form a neurobiological basis for explaining the drastic change in consciousness that occurs during this DMT flash (which is basically trying to figure out the means by which the DMT experience is created).
We are also going to try to show that the DMT experience cannot simply be explained away by typical modern neurobiological paradigms. Many scientists currently hold that the DMT experience is equivalent to another hallucinogenic or dream state without much nuance.
Neuronal representations of the world
In order to understand how DMT brings about the experience of such novel world’s, we need to first explore how the brain build’s and understands worlds.
We can break down the experience of the world into three key parts: the nature of the external world, the representation of the external world in our brain, and our subjective experience of the world in consciousness.
It’s important not to confuse our subjective experience of the world with the external world itself. In fact, it is widely agreed upon (and it makes complete sense intuitively after a bit of thought) that our experience of the world is not the world itself, but rather a projection of our consciousness.
If you are more curious about internalizing this concept or find yourself to be a bit skeptical, you might be interested in reading this blog post talking about this concept.
We also know that in order for the world to appear to our consciousness, there must be a neural representation of this world in our brain (this concept is also well supported by research — specifically brain lesion studies).
Thus, we know that the phenomenological experiences that are brought about by DMT and other psychedelics must also have neural representations in the brain.
How the brain represents the world
The brain’s representation of the world is largely encoded in the neurons of the neocortex. This representation of the world is largely determined by the functional segregation and integration that occurs in the neocortex.
The concept of functional segregation points at the fact that different parts of the brain encode different features of the world.
For example, pretend that we had a world in which there were only the colors red and blue, and the shapes of circles and squares, and each object in the world could only move left or right.
In short, the functional segregation of the brain refers to the fact that our brain in such a world would likely have on region for identifying the shape of what it sees, another for identifying the color, and a final area for identifying the direction of movement.
In the actual brain, the basic unit of functional segregation is though to me a cortical column, or a column of neurons in the neocortex. Each of these cortical columns is thought to encode a specific characteristic of the world.
Because of the massive amount of such units in the brain, with billions and billions of neurons, the brain is able to encode an unimaginable amount of combinations of such specific characteristics of the world, where each pattern of individual activations correlates with a neural representation of a single conscious moment in the world
Each of these columns in the neocortex maps onto a corresponding region in the thalamus such that these regions are connected, which is why we sometimes refer to the basic unit as the thalamocortical column rather than just the cortical column.
Each region of the thalamus maps back to multiple regions of the cortex, integrating multiple specific pieces of information together. This is the equivalent in our example of combining information of red, circle, and right together to understand that we see a red circle moving to the right.
Thus, we can consider the thalamocortical column as the fundamental unit of encoding information about the world, where the world is represented by different patterns of activation across the thalamocortical system.
In this way, we know that all conscious moments, including psychedelic ones, must be encoded in this thalamocortical loop.
Extrinsic and intrinsic information
Now that we have discussed (in brief) how our brain encodes its representation of our conscious states, we can talk about the two types of information relevant to the brain: extrinsic and intrinsic.
Extrinsic information is the information we receive from our senses from the outside world, like the things we see and what we hear for example.
Meanwhile, intrinsic information is the information that is reflected in the thalamocortical connections inside our brain. We know that the structure of these connections encodes possible representations of our conscious states.
It is important to not that extrinsic information doesn’t simply add to intrinsic information (that is, we don’t take both of these sources of information into account as their own parts).
Rather, extrinsic information about the world is matched up with the ongoing intrinsic information going on inside the brain. In other words, what we perceive in our waking state is a result of extrinsic information that we are receiving matching up with our internal model of the world encoded in our thalamocortical system.
However, it’s important to note that we can actually build full worlds from the intrinsic information in our brain’s in the lack of extrinsic information (this what the dreaming state is).
We can think about this as if the extrinsic information we receive constrains conscious perception to correspond with the existing similar intrinsic information in the brain.
Now the question of how this intrinsic information got into our brains in the first place arises.
Building our intrinsic model of the world through learning
In order to examine how our intrinsic model of the world is built, we must examine the two key characteristics of connectivity among neurons in the thalamocortical loop.
Structural connectivity refers to the physical connections between neurons in the brain. Meanwhile, functional connectivity refers to the representative connections between neurons that actually fire together in response to extrinsic information.
The key concept to understand here is that the intrinsic information that encodes our model of the brain is represented in the structural connectivity of our brain. However, this structural connectivity was not the same when we’re born.
Rather, the functional connectivity of neurons brought about by extrinsic information causes the structural connectivity of the brain to alter more toward the functional connections of neurons.
In this way, when we are young, the brain learns to build a model of the world that is represented in the structural connectivity of the neurons that is modulated by the extrinsic information coming in from the world.
Because of this influence of extrinsic data on our thalamocortical connections, the brain tends to form certain attractor states that are more likely to be active than others. What this looks like in practice is that out of all of the limitless possibilities of potential states of consciousness that we are able to experience, only the ones that reflect how the consensus world is form in our brain, which results in the intrinsic information in our brain corresponding more to consensus reality.
Thus, the waking state and ream state are both a result of intrinsic information, but the waking state is modulated by extrinsic information, where the dream state is not, as we have previously mentioned.
The question then becomes whether the DMT experience is completely a result of intrinsic information, or if it is in fact modulated by some kind of extrinsic information.
A quick look at the neurobiology of psychedelics
We can take a closer look at the mechanism of action of psychedelics in order to better understand how DMT may work.
Don’t worry if this section doesn’t make as much sense as it will get a bit technical. I will leave a summary of the most important points of the section at the end of it.
There are many neurotransmitters in the brain which are involved with signaling between neurons, but serotonin is the most important when it comes to the action of psychedelics.
Serotonin has many functions in the brain, but the most relevant to us is its use a neurotransmitter in some of the most important cells in the thalamocortical loop (called pyramidal cells).
These cells have many different kinds of serotonin receptors, which serotonin binds to and brings about various effects. Most notably are the 5HT1A and 5HT2A serotonin receptors.
These receptors maintain the balance of gamma oscillations in the thalamocortical loop — don’t worry if this doesn’t make sense right now, I’ll explain it in more detail soon. The 5HT2A receptor promotes gamma oscillations and the 5HT1A inhibits gamma oscillations.
Thus, maintaining the balance of activation of the 5HT2A and 5HT1A receptors is important for maintaining the balance of gamma oscillations in the thalamocortical loop.
The original balance of the 5HT2A and 5HT1A receptors is formed in the presence of serotonin. However, psychedelics bind to the 5HT2A receptors, which causes gamma oscillations to be promoted much more. This has 2 major effects: (1) the cortex becomes much more sensitive to incoming sensory data and (2) thalamocortical gamma oscillations are promoted even in the absence of incoming sensory data.
Most importantly, because of over activation of 5HT2A, pyramidal cells are more likely to enter into synchronized gamma oscillations. This effect spreads across the cortex as gamma oscillations stimulate the now easily excitable pyramidal cells and spread more freely through the cortex.
This effect could explain why sensory information often continues from one sense to another during psychedelic experiences, producing effects similar to synesthesia.
Established connectivities of thalamocortical system leads to attractor states that system tends toward (because of how they were formed modulated by extrinsic information) — this explains why even in absence of extrinsic info (ie dream state), system still tends toward states similar to consensus world.
In practice, this results in a temporary dissolution of the attractor states of the typical brain, where our consciousness is now more likely to experience states that are less correlated with the intrinsic model in our brain corresponding to consensus reality.
TL;DR: Psychedelics increase the number of available states to the thalamocortical system and shift our conscious perception from a more grounded one to a much more fluid one.
The nature of the DMT world
Now we can turn to the DMT experience and try to draw conclusions about its nature.
A common scientific opinion equates the DMT world to a dream world. However, we see that the dream world largely corresponds with the real world, which suggests that it is still influenced by the attractor states of the intrinsic information in our brain. This properly clearly does not hold for DMT and other psychedelics, so it is not feasible to simply equate DMT to another dream particle.
This points at the fact that DMT could not purely be a circumstance of the ongoing intrinsic information going on in our brain, since this intrinsic information corresponds so heavily with consensus reality and wouldn’t be able to produce the crazy experiences characteristic of DMT.
These makes it even more crazy how the brain can build DMT worlds, considering the unusual overlap between almost everyone’s DMT experiences.
Does extrinsic information modulate the DMT experience?
As mentioned above, it’s peculiar that so many people describe the same types of experiences on DMT, yet the experiences are so crazy and different from the typical intrinsic information in the brain.
Even if DMT worked by just bringing about unique thalamocortical states that are normally not represented in the intrinsic information of our brain, why would these random states coincide so much among every use of DMT?
This unlikely correlation may point at an extremely unconventional proposition — it may suggest that there is some extrinsic information modulating the DMT experience.
The presence of some extrinsic information during this experience would explain the uncanny similarity between the experiences of DMT users across the world involving alien world’s, unknown creatures, and complex emotions.
Of course, this is an extremely unconventional proposition, and there is no way to prove this yet, but it is certainly an interesting loose end to consider.
Could DMT be an ancestral neurotransmitter?
It’s also crazy to consider the fact that DMT is the simplest of the psychedelics and is so commonly found in nature, and yet it happens to produce effects so drastically different and more powerful than the other psychedelics.
It’s also curious how finely tuned the effect of DMT is in transferring humans to alien worlds, so its difficult to reconcile this fact with the idea that DMT is a randomly occurring drug who’s effect on humans is largely coincidental.
Recall that the thalamocortical columns encode states of the world, and are formed in the presence of serotonin as a result of extrinsic sensory data from the consensus world.
Overtime, these connections form a consensus set of connectivities that represent consensus reality. This consensus set is present when the 5HT1A and 5HT2A receptors are in relative balance
However, when DMT comes into the brain, it upsets the balance of 5HT2A receptors and the brain is altered and can adopt many more states. This state is what causes the psychedelic experience, but is only possible for the short amount of time that the drug is present in the brain.
We could then imagine that in the same way that in the presence of serotonin, the brain builds connectivities that are representative of the extrinsic data from the consensus world, in the presence of DMT, it is not that much of a conceptual stretch to suggest that in response to some other form of extrinsic data (of which kind we don’t know), the brain could form some kind of equivalent consensus set of data, which would only be active in the presence of DMT
If this were to happen, it would explain DMTs unique ability to transport users to alien worlds — this would happen because it was the neurotransmitter present in creating these consensus sets from extrinsic activity.
We know that there is currently nowhere close to enough DMT in the brain to act as a neuro-modulator and support this theory.
However, if at one point in the past DMT was a neuro-modulator in the brain, this scenario would be possible.
If ancestral humans had endogenous DMT, connections in the brain could form in the presence of DMT. If these connections formed in the presence of DMT were passed down through evolution, it would explain our unique response to DMT in comparison to other psychedelics. This would also explain why there are still pathways in the brain that produce trace amounts of DMT.
While this theory certainly makes a number of logical jumps, it is relatively plausible given the facts behind it. It’s by no means a definitive theory, but it’s definitely an interesting one with a creative line of thinking.
Hopefully, you’ve enjoyed reading this article and learning more detail about the biological mechanisms of DMT.
Thanks for reading!