May 28, 2021
How Entheogenic Plants & Fungi Affect Memory
Psilocybe mushroomsSource: Adobe Stock
A major area of psychedelic research is its potential clinical applications in psychiatry. In particular, a major area of study has concentrated on the potential therapeutic effects of shrooms, acid, and MDMA for treating post-traumatic stress disorder.
“Memory plays a central role in the psychedelic experience,” begins a 2020 Psychopharmacology review. “The ability for psychedelics to provoke vivid memories has been considered important to their clinical efficacy.”
Throughout their review, the researchers found that psychedelics enhance autobiographical memory recall, which has therapeutic potential for overcoming traumatic experiences. However, psychedelics also have a dose-dependent effect of impairing memory task performance.
The effects of psychedelics on memory aren’t a new discovery. As the review describes, half of the participants in the initial 1950 study on LSD experienced effects related to remembering childhood events.
Such observations, coupled with the dominance of psychotherapy throughout the mid-20th century, paved the way for “psycholytic therapy” — which literally translates to “mind-loosening therapy.” Psycholytic therapy refers to the practice of using low-to-moderate doses of LSD (or psilocybin) across multiple sessions to “facilitate, intensify, and deepen the psychoanalytic process,” the review explains.
By contrast, psycholytic therapy takes a psychoanalytic approach, whereas contemporary studies on psychedelic therapy typically focus on a single, high-dose session with the goal of producing “overwhelming” or “cosmic-mystic” experiences.
After assessing various studies on the effects of psychedelics on working memory, semantic memory, and non-autobiographical episodic memory, the researchers observed that psychedelics negatively affected the participants’ performance on tasks related to these types of memory. These effects are dose-dependent, with higher doses causing the most impairment (though it may be possible that experienced psychedelic users are more resilient to these effects).
Yet, autobiographical memory recall is significantly enhanced…
“While the autobiographical memories that arise during psychedelic experiences, especially in settings that are explicitly or implicitly therapeutic, may be highly personally meaningful and have a phenomenological quality of striking realness, uncritically accepting the accuracy and literality of these memories may have problematic implications,” the review states. “Both recovered memories of actual events, typically traumatic events, and false memories are empirically established phenomena with both clinical and experimental evidence.”
In other words, it’s possible these effects are somewhat biased. The psycholytic therapist may be indirectly (and unintentionally) influence the participant into creating a “false memory” of childhood trauma. Or the participant may go into the study expecting to remember forgotten trauma and unintentionally create a false memory.
Nevertheless, doubting the participants’ experiences could be incredibly damaging and harmful. Invisible wounds are still wounds. You wouldn’t look your child in their eyes and tell them they’re not bleeding after they’ve fallen off their bike and scraped their knee, would you?
Regardless of how accurate the autobiographical memories retrieved during psychedelic experiences are, the therapeutic effects of reliving and overcoming the perceived trauma are remarkably beneficial for the study participants. If it’s helping, isn’t that what matters most?
A similar issue is described throughout the New York Times Best-Seller “How to Change Your Mind” by Michael Pollan. While discussing mystic experiences occasioned by psychedelics with various researchers, Pollan concludes that the positive outcomes of such experiences are more important than the matters of how and if these mystical experiences are possible.
“Clinically, however, the accuracy of the memory the patient has recovered during a psychedelic experience — whether the memory is of an actual event, is entirely fantastic, or is the result of an interaction between fantasy and reality — may be less important than the effects experienced during the recovery and reliving of the memory and the meanings assigned to the memory after the experience,” the review says.
Backtracking slightly, let’s distance ourselves from the psychology of psychedelics and memory and dive more into the neurological bases for these effects. How do autobiographical memories differ from other types of memories in the brain? How do these differences come into play with the observed effects of psychedelics on memory?
A Brief Primer on Memory, Autobiographical Memories, and the Brain
“How We Make Memories” by Crash CourseSource: How We Make Memories: Crash Course Psychology #13 | Crash Course
Long-term v.s. short-term memory are probably the two most recognizable types of memory, but the classification of memory goes a bit further than that. According to Medical News Today, there’s some debate about how memories are classified, but most scientists agree there are at least four different types:
- Long-term memory: “Most memories, especially those older than about 30 seconds, are part of long-term memory,” the MNT article explains.
- Short-term memory: A limited string of information that’s retained for about 30 seconds. For example, a phone number before you jot it down.
- Working memory: Similar to short-term memory, working memory aids you in performing tasks like complex math problems or baking. Working memory is malleable and temporary, but it allows you to mentally keep track of what you’re doing as you’re performing a task.
- Sensory memory: Incredibly brief, your brain retains sensory information for one second or less. Sensory memory allows you to process the sights, sounds, scents, tastes, and sensations around you. If you pay attention to this sensory input, it may become a short-term or long-term memory.
Long-term memory can further be broken down into:
- Explicit long-term memory: Conscious memories of events, learned information, or autobiographical memories.
- Episodic memory: Memories of events, autobiographical memories, or personal facts.
- Semantic memory: General world knowledge. I.e. information you’ve learned about or studied, rather than events you personally experienced.
- Implicit long-term memory: Memories that subconsciously influence your behavior
- Procedural memory: Procedural memory helps you perform familiar tasks, such as riding a bike, driving a car, or walking
- Priming: This occurs when previous experiences influence your behavior. For example, craving a coffee every afternoon after making it a habit to pick up coffee during your lunch break, or another “conditioned response” (think: Pavlov’s Dogs).
As you can imagine, the different types of memory are stored across different areas of the brain. According to the Queensland Brain Institute, episodic memories are stored across the hippocampus, neocortex, and amygdala. The basal ganglia and cerebellum are involved in implicit memories. Working memory is stored in the prefrontal cortex, which is at the very front of the neocortex.
“Our memories may haunt us or sustain us, but either way, they define us,” American vlogger Hank Green says in the Crash Course video embedded above. “Without them, we are left to wander alone in the dark.”
Psychedelics & Memory: Taking a TRIP Down Memory Lane via Neuroanatomy
Pattern of psilocybin mushrooms on blue backgroundSource: Adobe Stock
The DMN is a set of brain regions that activate during resting brain states. Essentially, it’s where your mind wanders when you’re not actively engaged in a task. Beyond memory, the DMN also plays a role in motivation, addiction, pain, empathy, and mood regulation.
Psychedelics decrease functional connectivity in the DMN, which is believed to contribute to their therapeutic effects — especially in individuals who have depression, anxiety, obsessive-compulsive disorder, post-traumatic stress disorder, or substance use disorder.
If the DMN is producing intrusive memories or impulses, it makes sense that decreased DMN activity alleviates these symptoms.
Considering that there’s no “on/off” switch for the DMN, what’s occurring while tripping that causes the functional connectivity to decrease?
A 2020 study in the NeuroImage Journal proposes that psychedelics alter activity in the claustrum, which is a thin sheet-like structure of neurons underneath the inner surface of the neocortex.
Neuroanatomy chart showing where the claustrum is located in the brainSource: Malmstajn via WikiMedia Commons
Classic psychedelics are serotonin agonists that specifically bind to serotonin receptors 5-HT2A. A serotonin agonist is a substance that mimics the behavior of serotonin to activate different serotonin receptors in the brain.
Serotonin has many different functions throughout the brain and body, but 5-HT2A activation is associated with the psychedelic experience. The claustrum just so happens to have an abundance of 5-HT2A receptors — and the claustrum “provides glutamatergic inputs to all areas of the cerebral cortex,” the NeuroImage study explains.
More specifically, a 2005 Philosophical Transactions of the Royal Society B review states the claustrum is connected to the:
- Frontal lobe
- Motor cortex
- Prefrontal cortex
- Cingulate cortex
- Visual cortical regions
- Temporal and temporopolar cortex
- Frontoparietal operculum
- Somatosensory areas
- Prepiriform olfactory cortex
- Entorhinal Cortex
- Caudate nucleus
“The highly networked nature of the claustrum raises questions of whether it acts as a sort of ‘Cartesian theatre’,” the review continues. “This is a metaphor, introduced and ridiculed by the philosopher Dennett, for the fictitious center where the mind and brain meet, where ‘it all comes together’ and consciousness occurs.”
“We think that a more appropriate analogy for the claustrum is that of a conductor coordinating a group of players in the orchestra, the various cortical regions. Without the conductor, the players can still play but they fall increasingly out of synchrony with each other.”— F.C. Crick & C. Koch, 2005
Whether the claustrum is a “Cartesian theatre” or an “orchestral conductor,” it facilitates connections and communication between brain areas associated with multiple types of memory, emotional processing, and sensory processing.
In the context of studies that demonstrate how hallucinogens alter brain connectivity, induce different states of consciousness, alter memory processing, affect mood, and enhance sensory perception, psychedelic-induced changes in claustrum activity check out.
Hallucinogenic substances and the claustrum seem to go together like peanut butter and jelly, or two pieces of a puzzle. Or better yet, like a cat and dominos; the claustrum is the dominos and psychedelics are the playful cat that tips them over while you’re setting them up.
Entheogenic plants and fungi have long since been studied for their potential applications in clinical psychiatry. In particular, the potential benefits of psycholytic and psychedelic therapy for patients with PTSD, depression, anxiety, OCD, and SUD have been a central focus among researchers.
The potential benefits are usually related to study participants reliving and overcoming trauma while tripping in a clinical setting, which is a recurring theme in psychedelic studies.
While it appears psychedelics enhance autobiographical memory recall, they seem to negatively affect almost all other types of memory during a session. But memories are complex; there are different kinds of memory, which are stored and processed in different areas of the brain.
Autobiographical memories are stored and processed in the hippocampus, amygdala, and neocortex — all of which, are also associated with the default mode network. The default mode network is a set of regions that activate during resting brain states, but the pattern of activity changes while under the influence of psychedelics.
Recent research has demonstrated that another neuronal structure, the claustrum, also displays altered activity while tripping. The claustrum facilitates communication throughout all of the cerebral cortex (including regions associated with autobiographical memory) — which goes hand-in-hand with the widespread changes observed in psychedelic states.
These altered patterns of activity help explain why autobiographical memory recall is enhanced but other types of memory recall are decreased while tripping. Understanding these patterns is crucial to identifying potential applications for psychedelics in psychiatry.
But furthermore, observing these patterns and connections throughout the brain paves the way for a better understanding of ourselves; our thoughts, emotions, and consciousness.
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