Posts tagged psilocybin
Articles and news from the latest research reports.
New study discovers biological basis for magic mushroom ‘mind expansion’
Psychedelic drugs such as LSD and magic mushrooms can profoundly alter the way we experience the world but little is known about what physically happens in the brain. New research, published in Human Brain Mapping, has examined the brain effects of the psychedelic chemical in magic mushrooms, called psilocybin, using data from brain scans of volunteers who had been injected with the drug.
The study found that under psilocybin, activity in the more primitive brain network linked to emotional thinking became more pronounced, with several different areas in this network - such as the hippocampus and anterior cingulate cortex - active at the same time. This pattern of activity is similar to the pattern observed in people who are dreaming. Conversely, volunteers who had taken psilocybin had more disjointed and uncoordinated activity in the brain network that is linked to high-level thinking, including self-consciousness.
Psychedelic drugs are unique among other psychoactive chemicals in that users often describe ‘expanded consciousness,’ including enhanced associations, vivid imagination and dream-like states. To explore the biological basis for this experience, researchers analysed brain imaging data from 15 volunteers who were given psilocybin intravenously while they lay in a functional magnetic resonance imaging (fMRI) scanner. Volunteers were scanned under the influence of psilocybin and when they had been injected with a placebo.
“What we have done in this research is begin to identify the biological basis of the reported mind expansion associated with psychedelic drugs,” said Dr Robin Carhart-Harris from the Department of Medicine, Imperial College London. “I was fascinated to see similarities between the pattern of brain activity in a psychedelic state and the pattern of brain activity during dream sleep, especially as both involve the primitive areas of the brain linked to emotions and memory. People often describe taking psilocybin as producing a dream-like state and our findings have, for the first time, provided a physical representation for the experience in the brain.”
The new study examined variation in the amplitude of fluctuations in what is called the blood-oxygen level dependent (BOLD) signal, which tracks activity levels in the brain. This revealed that activity in important brain networks linked to high-level thinking in humans becomes unsynchronised and disorganised under psilocybin. One particular network that was especially affected plays a central role in the brain, essentially ‘holding it all together’, and is linked to our sense of self.
In comparison, activity in the different areas of a more primitive brain network became more synchronised under the drug, indicating they were working in a more co-ordinated, ‘louder’ fashion. The network involves areas of the hippocampus, associated with memory and emotion, and the anterior cingulate cortex which is related to states of arousal.
Lead author Dr Enzo Tagliazucchi from Goethe University, Germany said: “A good way to understand how the brain works is to perturb the system in a marked and novel way. Psychedelic drugs do precisely this and so are powerful tools for exploring what happens in the brain when consciousness is profoundly altered. It is the first time we have used these methods to look at brain imaging data and it has given some fascinating insight into how psychedelic drugs expand the mind. It really provides a window through which to study the doors of perception.”
Dr. Carhart-Harris added: “Learning about the mechanisms that underlie what happens under the influence of psychedelic drugs can also help to understand their possible uses. We are currently studying the effect of LSD on creative thinking and we will also be looking at the possibility that psilocybin may help alleviate symptoms of depression by allowing patients to change their rigidly pessimistic patterns of thinking. Psychedelics were used for therapeutic purposes in the 1950s and 1960s but now we are finally beginning to understand their action in the brain and how this can inform how to put them to good use.”
The data was originally collected at Imperial College London in 2012 by a research group led by Dr Carhart-Harris and Professor David Nutt from the Department of Medicine, Imperial College London. Initial results revealed a variety of changes in the brain associated with drug intake. To explore the data further Dr. Carhart-Harris recruited specialists in the mathematical modelling of brain networks, Professor Dante Chialvo and Dr Enzo Tagliazucchi to investigate how psilocybin alters brain activity to produce its unusual psychological effects.
As part of the new study, the researchers applied a measure called entropy. This was originally developed by physicists to quantify lost energy in mechanical systems, such as a steam engine, but entropy can also be used to measure the range or randomness of a system. For the first time, researchers computed the level of entropy for different networks in the brain during the psychedelic state. This revealed a remarkable increase in entropy in the more primitive network, indicating there was an increased number of patterns of activity that were possible under the influence of psilocybin. It seemed the volunteers had a much larger range of potential brain states that were available to them, which may be the biophysical counterpart of ‘mind expansion’ reported by users of psychedelic drugs.
Previous research has suggested that there may be an optimal number of dynamic networks active in the brain, neither too many nor too few. This may provide evolutionary advantages in terms of optimising the balance between the stability and flexibility of consciousness. The mind works best at a critical point when there is a balance between order and disorder and the brain maintains this optimal number of networks. However, when the number goes above this point, the mind tips into a more chaotic regime where there are more networks available than normal. Collectively, the present results suggest that psilocybin can manipulate this critical operating point.
Psilocybin inhibits the processing of negative emotions in the brain
When emotions are processed in a negatively biased manner in the brain, an individual is at risk to develop depression. Psilocybin, the bioactive component of the Mexican magic mushroom, seems to intervene positively in the emotion-processing mechanism. Even a small amount of the natural substance attenuates the processing of negative emotions and brightens mood as shown by UZH researchers using imaging methods.
Emotions like fear, anger, sadness, and joy enable people to adjust to their environment and react flexibly to stress and strain and are vital for cognitive processes, physiological reactions, and social behaviour. The processing of emotions is closely linked to structures in the brain, i.e. to what is known as the limbic system. Within this system the amygdala plays a central role – above all it processes negative emotions like anxiety and fear. If the activity of the amygdala becomes unbalanced, depression and anxiety disorders may develop.
Researchers at the Psychiatric University Hospital of Zurich have now shown that psilocybin, the bioactive component in the Mexican magic mushroom, influences the amygdala, thereby weakening the processing of negative stimuli. These findings could “point the way to novel approaches to treatment” comments the lead author Rainer Krähenmann on the results which have now been published in the renowned medical journal “Biological Psychiatry”.
Psilocybin inhibits the processing of negative emotions in the amygdala
The processing of emotions can be impaired by various causes and elicit mental disorders. Elevated activity of the amygdala in response to stimuli leads to the neurons strengthening negative signals and weakening the processing of positive ones. This mechanism plays an important role in the development of depression and anxiety disorders. Psilocybin intervenes specifically in this mechanism as shown by Dr. Rainer Krähenmann’s research team of the Neuropsychopharmacology and Brain Imaging Unit led by Prof. Dr. Franz Vollenweider.
Psilocybin positively influences mood in healthy individuals. In the brain, this substance stimulates specific docking sites for the messenger serotonin. The scientists therefore assumed that psilocybin exerts its mood-brightening effect via a change in the serotonin system in the limbic brain regions. This could, in fact, be demonstrated using functional magnetic resonance imaging (fMRI). “Even a moderate dose of psilocybin weakens the processing of negative stimuli by modifying amygdala activity in the limbic system as well as in other associated brain regions”, continues Krähenmann. The study clearly shows that the modulation of amygdala activity is directly linked to the experience of heightened mood.
Next study with depressive patients
According to Krähenmann, this observation is of major clinical importance. Depressive patients in particular react more to negative stimuli and their thoughts often revolve around negative contents. Hence, the neuropharmacologists now wish to elucidate in further studies whether psilocybin normalises the exaggerated processing of negative stimuli as seen in neuroimaging studies of depressed patients - and may consequently lead to improved mood in these patients.
Rainer Krähenmann considers research into novel approaches to treatment very important, because current available drugs for the treatment of depression and anxiety disorders are not effective in all patients and are often associated with unwanted side effects.
(Source: mediadesk.uzh.ch)
A good trip: Researchers are giving psychedelics to cancer patients to help alleviate their despair — and it’s working
On a bone-chilling morning in February last year, Nick Fernandez bundled up and took the subway from his Manhattan apartment to the Bluestone Center for Clinical Research, which is located in an art deco-style building on the Upper East Side. A 27-year-old graduate student in psychology with dark, wavy hair and delicate, bird-like features, Fernandez was excited and nervous. He had eaten a light breakfast consisting of a bagel and industrial-strength coffee in preparation for another journey he was about to take. Fernandez had signed up to be a subject in a New York University study into the use of psilocybin, the psychoactive ingredient in hallucinogenic mushrooms, to relieve mental anguish in people with terminal or recurrent cancer.
Fernandez hoped that the drug would lift the shroud of melancholy and free-floating anxiety that had enveloped him ever since he was diagnosed with leukemia in 2004 during his senior year in high school. Two and a half years of almost continuous chemotherapy vanquished the disease, but left him drained and traumatised. The former soccer star dropped more than 50 lbs from an already lean frame. ‘It was pretty brutal and forces you to grow up fast,’ said Fernandez, who became intensely interested in spiritual philosophy during this period, and went on to dabble in psychedelics in college. For years afterward, every sneeze and sniffle, every day that he felt tired or out of sorts, filled him with an unshakeable dread that the cancer had returned. When he heard the study mentioned on a radio show, he immediately signed up.
Jeffrey Guss and Erin Zerbo, the two NYU psychiatrists who would quietly monitor Fernandez’s progress throughout the day, greeted him when he arrived. After they took his vital signs, Fernandez changed into sweat pants and a shirt, and settled into a converted dental exam room that had been transformed into a hippie-style sanctum: tricked out with fresh flowers and fruits, a comfy sofa littered with plush pillows, Buddhist and shamanistic totems, and a high-tech sound system. Stephen Ross, an associate professor of psychiatry at NYU and the lead investigator for the study, made a brief appearance in the trip room. He was holding a glass vial that had been retrieved earlier that morning from a massive safe located inside a high-security storage room. It contained a single white capsule, and no one could be sure if it was a placebo – a dummy pill – or a 30 milligram dose of synthesised psilocybin.
Low doses of psychedelic drug erases conditioned fear in mice
Low doses of a psychedelic drug erased the conditioned fear response in mice, suggesting that the agent may be a treatment for post-traumatic stress disorder and related conditions, a new study by University of South Florida researchers found.
The unexpected finding was made by a USF team studying the effects of the compound psilocybin on the birth of new neurons in the brain and on learning and short-term memory formation. Their study appeared online June 2 in the journal Experimental Brain Research, in advance of print publication.
Psilocybin belongs to a class of compounds that stimulate select serotonin receptors in the brain. It occurs naturally in certain mushrooms that have been used for thousands of years by non-Western cultures in their religious ceremonies.
While past studies indicate psilocybin may alter perception and thinking and elevate mood, the psychoactive substance rarely causes hallucinations in the sense of seeing or hearing things that are not there, particularly in lower to moderate doses.
There has been recent renewed interest in medicine to explore the potential clinical benefit of psilocybin, MDMA and some other psychedelic drugs through carefully monitored, evidence-based research.
“Researchers want to find out if, at lower doses, these drugs could be safe and effective additions to psychotherapy for treatment-resistant psychiatric disorders or adjunct treatments for certain neurological conditions,” said Juan Sanchez-Ramos, MD, PhD, professor of neurology and Helen Ellis Endowed Chair for Parkinson’s Disease Research at the USF Health Morsani College of Medicine.
Dr. Sanchez-Ramos and his colleagues wondered about psilocybin’s role in the formation of short-term memories, since the agent binds to a serotonin receptor in the hippocampus, a region of the brain that gives rise to new neurons. Lead author for this study was neuroscientist Briony Catlow, a former PhD student in Dr. Sanchez-Ramos’ USF laboratory who has since joined the Lieber Institute for Brain Development, a translational neuroscience research center located in the Johns Hopkins Bioscience Park.
The USF researchers investigated how psilocybin affected the formation of memories in mice using a classical conditioning experiment. They expected that psilocybin might help the mice learn more quickly to associate a neutral stimulus with an unpleasant environmental cue.
To test the hypothesis, they played an auditory tone, followed by a silent pause before delivering a brief shock similar to static electricity. The mice eventually learned to link the tone with the shock and would freeze, a fear response, whenever they heard the sound.
Later in the study, the researchers played the sound without shocking the mice after each silent pause. They assessed how many times it took for the mice to resume their normal movements, without freezing in anticipation of the shock.
Regardless of the doses administered, neither psilocybin nor ketanserin, a serotonin inhibitor, made a difference in how quickly the mice learned the conditioned fear response. However, mice receiving low doses of psilocybin lost their fearful response to the sound associated with the unpleasant shock significantly more quickly than mice getting either ketanserin or saline (control group). In addition, only low doses of psilocybin tended to increase the growth of neurons in the hippocampus.
“Psilocybin enhanced forgetting of the unpleasant memory associated with the tone,” Dr. Sanchez-Ramos said. “The mice more quickly dissociated the shock from the stimulus that triggered the fear response and resumed their normal behavior.”
The result suggests that psilocybin or similar compounds may be useful in treating post-traumatic stress disorder or related conditions in which environmental cues trigger debilitating behavior like anxiety or addiction, Dr. Sanchez-Ramos said.