Foundational Concepts in the Neurobiology of Psychedelics Flashcards
What neural mechanisms are activated when a psychedelic substance is introduced into the body, and how do these correlate with the experiential changes observed?
When a psychedelic substance such as psilocybin or LSD is introduced into the body, it primarily interacts with the serotonin 5-HT2A receptors in the brain. This interaction results in a cascade of changes in brain function, notably an increase in neural plasticity and a decrease in default mode network activity, which is associated with self-referential thoughts.
These changes correlate with experiences of ego dissolution, altered perception, and heightened emotional states.
However, capturing the full spectrum of subjective experiences—like mystical or transformative experiences—through purely neurological explanations remains a challenge, as these experiences may transcend the current reductionist frameworks in neuroscience.
What is Neural correlates of experience?
Changes in measured activity of the human nervous system that correlate with reports of subjective experiential changes.
What are the Big 4 atoms for describing organisms?
Hydrogen, carbon, nitrogen, oxygen: constitute ~96.5% of a living human body.
What is an Atom?
Elemental chemical components of the matter.
What is Hydrogen?
The lightest chemical element. Nucleus contains one positively-charged proton.
What is Uranium?
The heaviest chemical element known to occur naturally on Earth. Nucleus contains 92 positively-charged protons.
Elements heavier than uranium produced in laboratories (beginning in 1940) by smashing atoms together in a device called the cyclotron. Currently there are 26 known transuranium elements (numbers 93 to 118 on the periodic table). The known transuranium elements are unstable and have relatively short lifetimes, which is why they have not been found to occur naturally on the Earth.
What is Chemical bond?
Sharing of electrons between atoms, forming the “glue” holding atoms together in a molecule. Hydrogen can form one bond, oxygen two bonds, nitrogen three bonds, and carbon four bonds.
What is the interactions between neurotransmitter systems in the brain and psychedelic molecules are complex?
Serotonin Receptor Agonism: Many classic psychedelics, such as LSD, psilocybin, and DMT, primarily act as agonists at serotonin 5-HT2A receptors. This interaction is a significant driver of their psychoactive effects. The activation of these receptors affects various neural circuits, which can alter perception, mood, and cognition.
Modulation of Brain Networks: Psychedelics have been shown to disrupt the activity of the default mode network (DMN), which is involved in self-referential thought processes, such as daydreaming and self-reflection. This disruption is associated with the feelings of ego dissolution that many users report and may be linked to the therapeutic effects of psychedelics on conditions like depression.
Neuroplasticity: Recent research suggests that psychedelics may promote neuroplasticity — the brain’s ability to form new neural connections. This can potentially lead to lasting changes in brain structure and function, contributing to their effects on various psychiatric disorders.
Cross-Talk Between Neurotransmitter Systems: While the primary action is on the serotonin system, psychedelics can also influence other neurotransmitter systems either directly or indirectly, including dopamine and glutamate pathways. This can affect various functions and behaviors, from emotional regulation to sensory perception.
Changes in Brain Blood Flow and Metabolism: Psychedelics can alter cerebral blood flow and the metabolism of different brain regions. This can lead to enhanced sensory perception and altered states of consciousness.
What is a Protein?
Large biological molecules, typically consisting of thousands of atoms, and serving diverse structural and functional roles in organisms.
What is Amino acids?
Molecular subunits of proteins; proteins are composed of chains of several hundred amino acids linked together by chemical bonds; the entire structure folds into a 3-dimensional shape that serves a particular function (e.g., a receptor for the neurotransmitter serotonin).
What term is used in pharmacology to describe a substance that activates a receptor, such as how classical psychedelics activate the serotonin 2A receptor?
The term used in pharmacology to describe a substance that activates a receptor is “agonist.” Classical psychedelics are known to be agonists of the serotonin 2A receptor.
What is a Critical period?
A temporal stage, generally associated with organismal development, during which the nervous system is particularly sensitive to changing (neuroplasticity) in association with particular environmental stimuli.
How are the active compounds in psychedelics and other substances, such as mushrooms and tobacco, referred to in terms of their molecular structure?
In the context of their molecular structures, the active compounds in substances like mushrooms and tobacco are referred to by their specific chemical names.
For example, the active psychedelic compound in mushrooms is psilocybin, while the primary active compound in tobacco is nicotine. These names reflect the specific molecules responsible for the effects of these substances.
How are specific molecules in various substances associated with particular neurotransmitter systems in the brain?
Different psychoactive substances contain specific molecules that interact with particular neurotransmitter systems in the brain. For instance:
Psilocybe mushrooms contain psilocybin, which primarily affects the serotonin system.
Peyote or San Pedro cacti contain mescaline, also primarily interacting with the serotonin system.
Cannabis contains delta-9-tetrahydrocannabinol (THC), which influences the endocannabinoid system.
Opium contains morphine, which targets the endogenous endorphin system, involved in pain relief.
Common stimulants like coffee, tea, and cacao contain caffeine, which affects the adenosine neural signaling system by blocking adenosine receptors, leading to increased alertness and wakefulness.
Why is it important to consider the cultural context and traditional uses of psychoactive substances when integrating them into Western medicine?
Integrating psychoactive substances from traditional settings into Western medicine requires an understanding of their cultural context and traditional uses. This approach acknowledges the holistic nature of healing practices among Indigenous communities, where rituals and community involvement play critical roles.
For instance, in the traditional use of ibogaine, the entire community engages in supporting the individual, with practices such as face painting and guided experiences that enhance the drug’s therapeutic effects. Overlooking these cultural practices might lead to missing key elements that contribute to the substance’s efficacy.
