Magic mushrooms and the amygdala

People have been eating psychedelic mushrooms since ancient times. There are even indications--although they are impossible to verify--that psychedelic mushrooms played an important role in cultures like the Mayan civilizations of South America thousands of years ago. Of course, the use of "magic" mushrooms has continued into the present day, but it wasn't until 1958 that Albert Hofmann (the discoverer of LSD) isolated psilocybin as the active hallucinogenic compound in psychedelic mushrooms.

Recently, psilocybin has also received some recognition as a potential treatment for anxiety. For example, a pilot study conducted in 2011 explored the ability of psilocybin to reduce anxiety in individuals with advanced stage cancer. Although it was a small study and only exploratory in nature, it suggested that psilocybin could have some benefit in reducing anxiety and improving mood in patients with a terminal illness.

In a study due to be published soon in Biological Psychiatry, a research group in Switzerland explored a potential mechanism for reduced anxiety after psilocybin administration. The authors, Kraehenmann et al., administered psilocybin or placebo to a group of participants. Then, they monitored the participants' brain activity using functional magnetic resonance imaging (fMRI) while the subjects completed a task that generally increases activation in an area of the brain called the amygdala. The task involved viewing a series of pictures; half of the pictures presented negative stimuli like a car accident, and the other half presented neutral pictures like everyday objects or scenes from daily life.

The amygdala is an almond-shaped collection of nuclei in the temporal lobe (there are actually two amygdalae--one in each hemisphere). Increased activity in the amygdala has been associated with emotional reactions, and especially with fear and anxiety. Hyperactivity in the amygdala has also been observed in depressed patients, and treatment with selective serotonin reuptake inhibitors (SSRIs) has been found to reduce that hyperactivity. This suggests that increased activity in the amygdala may also play a role in symptoms of depression.

Kraehenmann et al. found that psilocybin administration improved mood and decreased anxiety, which was to be expected (magic mushrooms acquired their moniker for a reason). The study, however, also offered some insight into what might be causing that reduction in anxiety. After taking psilocybin (as compared to placebo), activity in the right amygdala was reduced while viewing negative images, and activity in the left amygdala was decreased in response to both negative and neutral images.

Psilocybin is thought to act as an agonist at serotonin receptors, meaning it increases serotonin transmission. Thus, it may be that antidepressants like SSRIs that act on serotonin--at least as part of their mechanism--have something in common with psilocybin. And, it suggests that perhaps psilocybin should continue to be investigated for its antidepressant and anxiolytic (anti-anxiety) properties.

Kraehenmann, R., Preller, K., Scheidegger, M., Pokorny, T., Bosch, O., Seifritz, E., & Vollenweider, F. (2014). Psilocybin-Induced Decrease in Amygdala Reactivity Correlates with Enhanced Positive Mood in Healthy Volunteers Biological Psychiatry DOI: 10.1016/j.biopsych.2014.04.010

YOUR BRAIN, EXPLAINED

Sleep. Memory. Pleasure. Fear. Language. We experience these things every day, but how do our brains create them? Your Brain, Explained is a personal tour around your gray matter. Building on neuroscientist Marc Dingman’s popular YouTube series, 2-Minute Neuroscience, this is a friendly, engaging introduction to the human brain and its quirks using real-life examples and Dingman’s own, hand-drawn illustrations.

An informative, accessible and engaging book for anyone who has even the slightest interest in how the brain works, but doesn’t know where to begin. - Dean Burnett, PhD, author, Happy Brain and Idiot Brain
Reading like a collection of detective stories, Your Brain, Explained combines classic cases in the history of neurology with findings stemming from the latest techniques used to probe the brain’s secrets. - Stanley Finger, PhD, Professor Emeritus of Psychological & Brain Sciences, Washington University (St. Louis), author, Origins of Neuroscience
Dingman weaves classic studies with modern research into easily digestible sections, to provide an excellent primer on the rapidly advancing field of neuroscience. - Moheb Costandi, author, Neuroplasticity and 50 Human Brain Ideas You Really Need to Know
...a highly readable and accessible introduction to the operation of the brain and current issues in neuroscience... a wonderful introduction to the field. - Frank Amthor, PhD, Professor of Psychology, The University of Alabama at Birmingham, author, Neuroscience for Dummies

Order Now

BIZARRE

This book shows a whole other side of how brains work by examining the most unusual behavior to emerge from the human brain. In it, you'll meet a woman who is afraid to take a shower because she fears her body will slip down the drain, a man who is convinced he is a cat, a woman who compulsively snacks on cigarette ashes, and many other unusual cases. As uncommon as they are, each of these cases has something important to teach us about everyday brain function.

Bizarre is a collection of stories of how the brain can create zombies, cult members, extra limbs, instant musicians, and overnight accents, to name a few of the mind-scratching cases. After reading this book, you will walk away with a greater appreciation for this bizarre organ. If you are a fan of Oliver Sacks' books, you're certain to be a fan of Dingman's Bizarre. - Allison M. Wilck, PhD, Researcher and Assistant Professor of Psychology, Eastern Mennonite University
Dingman brings the history of neuroscience back to life and weaves in contemporary ideas seamlessly. Readers will come along for the ride of a really interesting read and accidentally learn some neuroscience along the way. - Erin Kirschmann, PhD, Associate Professor of Psychology & Counseling, Immaculata University
Through case studies of both exceptional people as well as those with disorders, Bizarre takes us on a fascinating journey in which we learn more about what is going on in our skull. - William J. Ray, PhD, Emeritus Professor of Psychology, The Pennsylvania State University, author, Abnormal Psychology
A unique combination of storytelling and scientific explanation that appeals to the brain novice, the trained neuroscientist, and everyone in between. Dingman explores some of the most fascinating and mysterious expressions of human behavior in a style that is case study, dramatic novel, and introductory textbook all rolled into one. - Alison Kreisler, PhD, Neuroscience Instructor, California State University, San Marcos