Plants of power healing ceremony

Advancements in the past few years have revolutionized our understanding of how psilocybin works in the brain. The prevailing theory also comes from Imperial College London’s Psychedelic Research Center where in 2012, Carhart-Harris and colleagues began scanning the brains of study participants on psilocybin using fMRI, expecting to find an increased amount of activity. What they found instead was a substantial decrease in activity in brain regions that make up the Default Mode Network (DMN). In fact, the more intense the journey, the less activity they saw in the DMN. But what does that mean? What does the DMN even do in “normal” waking life?

The DMN, sometimes referred to as the gravity center of the brain, is responsible for the high-level aspects of consciousness that essentially make us human, like sense of self, worry, self-referential thinking, autobiographical memory, conserving the perspective of others, planning for the future, moral decision making, and self-consciousnesses. The DMN helps us tell the story of ourselves, or our “ego,” as well as navigate social situation by using past experiences to help us make decisions and plan for the future. “It helps you to identify and codify what is important to you, what you value, what you fear, what you dislike,” says James Giordano, professor of neurology and biochemistry at Georgetown University Medical Center. The DMN is a big part of what distinguishes us from other mammals, but an overactive system is also thought to be responsible for things like excessive rumination and overly negative self-critical thoughts that are common in mental health condition like depression, anxiety, addiction, obsessive-compulsive disorder, eating disorders, and others.

And so, what happens when you turn the volume down on your Default Mode Network? While on psilocybin, instead of staying stuck in the same old narrative—or having the same parts of the brain communicate—now the brain makes new, novel connections, a theory Carhart-Harris has dubbed the “entropic” or “anarchic” brain theory. This action is where researchers believe most of the acute subjective effects, like ego dissolution and insights, as well as visual and auditory distortions, lie, not to mention the root of psilocybin’s potential for personal growth. That’s because, researchers like Watts and Carhart-Harris speculate, it is in the psilocybin-induced “chaotic” state that the brain becomes more flexible and less dominated by the everyday narrative we tell ourselves, which in the case of some psychiatric condition, are actually harming us and holding us back. In recent years, Carthart-Harris has refined this theory, now calling the REBUS model (Relaxed Beliefs Under pSychedelics)— theorizing that when the psychedelics relax our DMN and its “high-level belief,” then the brain has more communication with older, instinctual parts of itself, like the limbic system. Watts writes, “This liberated upwards limbic flow can disrupt unhelpful entrenched beliefs. Instead of being constrained to a small number of ‘gravitationally dominant attractors’, the mind and brain freely transitions between states, which can feel like the mind is ‘opening up.’”

Watts explains, “Our brain is like a skier that ordinarily follows the well-trodden tracks. The psilocybin experience can temporarily disrupt and flatten the old grooves in the snow, setting up the possibility that new tracks may be laid down. Essentially psychedelic administration can foster new, short-term flexibility and the ability to start new habits of thinking, acting, and feeling.” She does go on to explain that the new habits must be practiced in order to “consolidate new learning,” basically explaining the impotence of integration. “In other words, the new tracks need to be worn well enough to prevent one from reverting to old tracks too easily.” Basically, your ingrained day-to-day narrative of yourself is disputed, giving you the opportunity to see yourself and your world differently for the duration of the trip. It makes sense, considering how people describe psychedelics as giving them a “new perspective” or a “new self-concept,” but what you do with that new perspective depends on your actions moving forward. And so, even if your brain is altered for a few hours, it’s up to you to take these insights and apply them to your life in order to enact any personal growth. Simply taking mushrooms alone likely won’t change who you are, but if you practice new ways of being, maybe you won’t get stuck in the same rut.

How do mushrooms quiet the Default Mode Network? It all has to do with the brain’s serotonin system. Let’s back up a little. When you eat magic mushrooms or take a psilocybin capsule, it’s actually metabolized into the prodrug psilocin. When psilocin reaches your brain, it triggers the serotonin system, specifically the serotonin receptor: 5-HT2A (which we’ll just call the 2A receptor from now on.” Unsurprisingly, the brain regions with the most 2A receptors are part of the Default Mode Network, and thus part of our “higher level” brain systems. When psilocin acts on 2A receptors, it initiates the quieting of the DMN and the novel brain connections that follow. Basically 2A receptors are psychedelics’ “trigger points.” In fact, researchers have found that if 2A receptors are “turned off” first, like if using a 2A antagonist, then psychedelics don’t produce the signature “mind revealing” effect. 

Serotonin 2A receptors play a role in a lot of really interesting behaviors. For instance, Carhart-Harris writes that 2A signaling has been shown to play a role in cognitive flexibility. There have also been links between “trait pessimism,” like “pathological brooding” and deficient 2A receptor stimulation. Both of these roles of 2A receptors make sense considering how people use psychedelics for personal growth, but some of the most interesting links between the serotonin system and psychedelics have to do with neural plasticity. Essentially, researchers have found evidence that 2A signaling may enhance neural plasticity, meaning that psychedelics may be able to promote brain plasticity by acting on those receptors.

But what is neural plasticity exactly? Basically, it used to be believed that the brain stopped changing structurally after childhood, but now scientists know that the brain continues to change and adapt based on things like learning, environment, and even damage. There are two types of neuroplasticity: functional plasticity and structural plasticity. Functional plasticity is the brain’s ability to redirect functions from a damaged area of the brain to a healthier one. Structural plasticity, on the other hand, is the brain’s capacity to change its physical stricture as a result of learning. And scientists at the University of California, Davis, found that psilocin and other psychedelics are able to promote both kinds of plasticity in cortical neurons. 

This is important for a few reasons, but the researchers themselves indicate that a common physical symptom of depression and other related mental health conditions is the atrophy of neurons in the prefrontal cortex, an area of the brain that plays a large role in mood, emotion, and anxiety regulation. What they found was the psychedelics like psilocin, LSD, and DMT were able to robustly promise neuritogenesis (new growth from neurons), therefore potentially counteracting depression’s detrimental effect on those same neurons. What’s more, they found that this same process is mediated by our favorite serotonin receptors: 2A. And so, Earhart-Harris has recently theorized that when the brain enters its “entropic” she on psychedelics where the DMN is quieted, it creates a “window of high plasticity” that may be able to change the brain even once the psychedelic substances have worn off.

So how does psilocybin work? It appears to have a twofold approach. Its effects on the brain not only gives people access to a new perspective, insights and lessons they can use to better their lives, but sometimes even full-blown mystical experiences that can change their sense of self-concept and motivate them to be the best versions of themselves. That same process also seems to have potentially long-lasting structural effects on our brains, especially those under siege of depression and other similar conditions. It’s not two separate actions but one fully integrated experience, especially if you’ve prepared a supportive and safe set and setting. It’s mystical to say the least, and amazing that this is all from a substance found in fungi that grow wild around the world.

**Excerpt from Your Psilocybin Mushroom Companion, by Michelle Janikian