OPEN Foundation

Mushrooms / Psilocybin

Pharmacology of Hallucinations: Several Mechanisms for One Single Symptom?

June 4, 2014 / LSD, Mushrooms / Psilocybin, Neuroscience, Papers, Psychology, Psychopharmacology, Psychosis, Publications / By / , , , , ,

Abstract

Hallucinations are complex misperceptions, that principally occur in schizophrenia or after intoxication induced by three main classes of drugs: psychostimulants, psychedelics, and dissociative anesthetics. There are at least three different pharmacological ways to induce hallucinations: (1) activation of dopamine D2 receptors (D2Rs) with psychostimulants, (2) activation of serotonin 5HT2A receptors (HT2ARs) with psychedelics, and (3) blockage of glutamate NMDA receptors (NMDARs) with dissociative anesthetics. In schizophrenia, the relative importance of NMDAR and D2R in the occurrence of hallucinations is still debated. Slight clinical differences are observed for each etiology. Thus, we investigated whether the concept of hallucination is homogenous, both clinically and neurobiologically. A narrative review of the literature is proposed to synthesize how the main contributors in the field have approached and tried to solve these outstanding questions. While some authors prefer one explanatory mechanism, others have proposed more integrated theories based on the different pharmacological psychosis models. In this review, such theories are discussed and faced with the clinical data. In addition, the nosological aspects of hallucinations and psychosis are addressed. We suggest that if there may be common neurobiological pathways between the different pharmacological systems that are responsible for the hallucinations, there may also be unique properties of each system, which explains the clinical differences observed.

Rolland, B., Jardri, R., Amad, A., Thomas, P., Cottencin, O., & Bordet, R. (2014). Pharmacology of Hallucinations: Several Mechanisms for One Single Symptom? Biomed Research International. http://dx.doi.org/10.1155/2014/307106
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The effects of psilocybin and MDMA on between-network resting state functional connectivity in healthy volunteers

May 27, 2014 / Consciousness, MDMA, Mushrooms / Psilocybin, Neuroscience, Papers, Psychology, Psychopharmacology, Publications / By / , , , ,

Abstract

Perturbing a system and observing the consequences is a classic scientific strategy for understanding a phenomenon. Psychedelic drugs perturb consciousness in a marked and novel way and thus are powerful tools for studying its mechanisms. In the present analysis, we measured changes in resting-state functional connectivity (RSFC) between a standard template of different independent components analysis (ICA)-derived resting state networks (RSNs) under the influence of two different psychoactive drugs, the stimulant/psychedelic hybrid, MDMA, and the classic psychedelic, psilocybin. Both were given in placebo-controlled designs and produced marked subjective effects, although reports of more profound changes in consciousness were given after psilocybin. Between-network RSFC was generally increased under psilocybin, implying that networks become less differentiated from each other in the psychedelic state. Decreased RSFC between visual and sensorimotor RSNs was also observed. MDMA had a notably less marked effect on between-network RSFC, implying that the extensive changes observed under psilocybin may be exclusive to classic psychedelic drugs and related to their especially profound effects on consciousness. The novel analytical approach applied here may be applied to other altered states of consciousness to improve our characterization of different conscious states and ultimately advance our understanding of the brain mechanisms underlying them.

Roseman, L., Leech, R., Feilding, A., Nutt, D. J., & Carhart-Harris, R. L. (2014). The effects of psilocybin and MDMA on between-network resting state functional connectivity in healthy volunteers. Frontiers in Human Neuroscience, 8, 1-11. http://dx.doi.org/10.3389/fnhum.2014.00204
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The effect of psilocin on memory acquisition, retrieval, and consolidation in the rat

May 16, 2014 / Mushrooms / Psilocybin, Neuroscience, Other subjects, Papers, Psychopharmacology, Publications / By / , , ,

Abstract

The involvement of the serotonin system in the pathophysiology of schizophrenia has been elucidated by experiments with hallucinogens. Application of a hallucinogen to humans leads to changes in perception, cognition, emotions, and induction of psychotic-like symptoms that resemble symptoms of schizophrenia. In rodent studies, their acute administration affects sensorimotor gating, locomotor activity, social behavior, and cognition including working memory, the phenotypes are considered as an animal model of schizophrenia. The complexity and singularity of human cognition raises questions about the validity of animal models utilizing agonists of 5-HT2A receptors. The present study thus investigated the effect of psilocin on memory acquisition, reinforced retrieval, and memory consolidation in rats. Psilocin is a main metabolite of psilocybin acting as an agonist at 5-HT2A receptors with a contribution of 5-HT2C and 5-HT1A receptors. First, we tested the effect of psilocin on the acquisition of a Carousel maze, a spatial task requiring navigation using distal cues, attention, and cognitive coordination. Psilocin significantly impaired the acquisition of the Carousel maze at both doses (1 and 4 mg/kg). The higher dose of psilocin blocked the learning processes even in an additional session when the rats received only saline. Next, we examined the effect of psilocin on reinforced retrieval and consolidation in the Morris water maze (MWM). The dose of 4 mg/kg disrupted reinforced retrieval in the MWM. However, the application of a lower dose was without any significant effect. Finally, neither the low nor high dose of psilocin injected post-training caused a deficit in memory consolidation in the MWM. Taken together, the psilocin dose dependently impaired the acquisition of the Carousel maze and reinforced retrieval in MWM; however, it had no effect on memory consolidation.

Rambousek, L., Palenicek, T., Vales, K., & Stuchlik, A. (2014). The effect of psilocin on memory acquisition, retrieval, and consolidation in the rat. Frontiers in Behavioral Neuroscience, 8. https://dx.doi.org/10.3389/fnbeh.2014.00180
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Interaction of psychoactive tryptamines with biogenic amine transporters and serotonin receptor subtypes

May 7, 2014 / DMT, LSD, MDMA, Mushrooms / Psilocybin, Other subjects, Papers, Psychopharmacology, Publications / By / , , , , ,

Abstract

Rationale
Synthetic hallucinogenic tryptamines, especially those originally described by Alexander Shulgin, continue to be abused in the USA. The range of subjective experiences produced by different tryptamines suggests that multiple neurochemical mechanisms are involved in their actions, in addition to the established role of agonist activity at serotonin 2A (5-HT2A) receptors.

Objectives
This study evaluated the interaction of a series of synthetic tryptamines with biogenic amine neurotransmitter transporters and with serotonin (5-HT) receptor subtypes implicated in psychedelic effects.

Methods
Neurotransmitter transporter activity was determined in rat brain synaptosomes. Receptor activity was determined using calcium mobilization and DiscoveRx PathHunter® assays in HEK293, Gα16-CHO, and CHOk1 cells transfected with human receptors.

Results
Twenty-one tryptamines were analyzed in transporter uptake and release assays, and 5-HT2A, serotonin 1A (5-HT1A), and 5-HT2A β-arrestin functional assays. Eight of the compounds were found to have 5-HT-releasing activity. Thirteen compounds were found to be 5-HT uptake inhibitors or were inactive. All tryptamines were 5-HT2A agonists with a range of potencies and efficacies, but only a few compounds were 5-HT1A agonists. Most tryptamines recruited β-arrestin through 5-HT2A activation.

Conclusions
All psychoactive tryptamines are 5-HT2A agonists, but 5-HT transporter (SERT) activity may contribute significantly to the pharmacology of certain compounds. The in vitro transporter data confirm structure-activity trends for releasers and uptake inhibitors whereby releasers tend to be structurally smaller compounds. Interestingly, two tertiary amines were found to be selective substrates at SERT, which dispels the notion that 5-HT-releasing activity is limited only to primary or secondary amines.

Blough, B. E., Landavazo, A., Decker, A. M., Partilla, J. S., Baumann, M. H., & Rothman, R. B. (2014). Interaction of psychoactive tryptamines with biogenic amine transporters and serotonin receptor subtypes. Psychopharmacology, 231(21), 4135-4144. http://dx.doi.org/10.1007/s00213-014-3557-7
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Psilocybin-Induced Decrease in Amygdala Reactivity Correlates with Enhanced Positive Mood in Healthy Volunteers

April 26, 2014 / Depression, Mushrooms / Psilocybin, Neuroscience, Papers, Psychology, Psychopharmacology, Publications / By / , , , , , ,

Abstract

Background
The amygdala is a key structure in serotonergic emotion-processing circuits. In healthy volunteers, acute administration of the serotonin 1A/2A/2C receptor agonist psilocybin reduces neural responses to negative stimuli and induces mood changes toward positive states. However, it is little-known whether psilocybin reduces amygdala reactivity to negative stimuli and whether any change in amygdala reactivity is related to mood change.

Methods
This study assessed the effects of acute administration of the hallucinogen psilocybin (.16 mg/kg) versus placebo on amygdala reactivity to negative stimuli in 25 healthy volunteers using blood oxygen level-dependent functional magnetic resonance imaging. Mood changes were assessed using the Positive and Negative Affect Schedule and the state portion of the State-Trait Anxiety Inventory. A double-blind, randomized, cross-over design was used with volunteers counterbalanced to receive psilocybin and placebo in two separate sessions at least 14 days apart.

Results
Amygdala reactivity to negative and neutral stimuli was lower after psilocybin administration than after placebo administration. The psilocybin-induced attenuation of right amygdala reactivity in response to negative stimuli was related to the psilocybin-induced increase in positive mood state.

Conclusions
These results demonstrate that acute treatment with psilocybin decreased amygdala reactivity during emotion processing and that this was associated with an increase of positive mood in healthy volunteers. These findings may be relevant to the normalization of amygdala hyperactivity and negative mood states in patients with major depression.

Kraehenmann, R., Preller, K. H., Scheidegger, M., Pokorny, T., Bosch, O. G., Seifritz, E., & Vollenwieder, F. X. (2014). Psilocybin-Induced Decrease in Amygdala Reactivity Correlates with Enhanced Positive Mood in Healthy Volunteers. Biological Psychiatry. http://dx.doi.org/10.1016/j.biopsych.2014.04.010
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Classical hallucinogens as antidepressants? A review of pharmacodynamics and putative clinical roles

March 17, 2014 / Anxiety disorders / PTSD, Depression, Mushrooms / Psilocybin, Neuroscience, Papers, Psychiatry, Psychology, Psychopharmacology, Psychotherapy, Publications / By / , , ,

Abstract

Hallucinogens have been part of spiritual practice for millennia, but controversy surrounding their mind-manifesting effects led to their proscription by the mid-20th century, largely without evidence of harm or toxicity and despite nascent data suggesting therapeutic utility in treating depressive illnesses. This review explores their pharmacodynamic actions and the current limited data on their clinic effectiveness. These drugs appear to exert their psychedelic effects through their agonist or partial agonist activity at the serotonergic 5-HT2A receptor, though they also have affinity for other metabotropic serotonin receptors. Hallucinogen binding affects a wide range of intracellular signalling pathways, the precise nature of which remains incompletely understood. They alter the serotonergic tone of brainstem raphe nuclei that project through the brain; they interact with receptors in the prefrontal cortex altering connectivity patterns and intracellular functioning; and they disrupt inhibitory control of sensory input via the thalamus to the cortex. The serotonergic system has long been implicated in anxiety and depressive disorders, and is a major target of most existing antidepressants. Classical hallucinogens alter the functioning of this system, but not in the same way current medications do: whilst there are identified receptors and neurotransmitter pathways through which hallucinogens could therein produce therapeutic effects, the neurobiology of this remains speculative at this time. There is currently an extremely limited but growing literature on hallucinogen safety and clinical application. The drugs appear well tolerated by healthy controls and clinical populations, and the rapid tolerance to repeated administration might reduce the possibility of dependency. Clinical trials reported over the past decade have generally shown positive therapeutic potential, but they are notably few in number. Legislative policy has had a freezing effect on evaluation of these compounds, a better understanding of which might improve our knowledge of the processes involved in consciousness, the neuropathology of depression, and potentially open up new pharmacological therapies.

Baumeister, D., Barnes, G., Giaroli, G., & Tracy, D. (2014). Classical hallucinogens as antidepressants? A review of pharmacodynamics and putative clinical roles. Therapeutic Advances in Psychopharmacology, 4(4), 156-159. http://dx.doi.org/10.1177/2045125314527985
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Why Psychiatry Needs Psychedelics and Psychedelics Need Psychiatry

March 11, 2014 / Addiction, Anxiety disorders / PTSD, Depression, LSD, MDMA, Mushrooms / Psilocybin, Papers, Psychiatry, Psychology, Psychotherapy, Publications / By /

Abstract

Without researching psychedelic drugs for medical therapy, psychiatry is turning its back on a group of compounds that could have great potential. Without the validation of the medical profession, the psychedelic drugs, and those who take them off-license, remain archaic sentiments of the past, with the users maligned as recreational drug abusers and subject to continued negative opinion. These two disparate groups—psychiatrists and recreational psychedelic drug users—are united by their shared recognition of the healing potential of these compounds. A resolution of this conflict is essential for the future of psychiatric medicine and psychedelic culture alike. Progression will come from professionals working in the field adapting to fit a conservative paradigm. In this way, they can provide the public with important treatments and also raise the profile of expanded consciousness in mainstream society.

Sessa, B. (2014). Why Psychiatry Needs Psychedelics and Psychedelics Need Psychiatry. Journal of Psychoactive Drugs, 46(1), 57–62. http://dx.doi.org/10.1080/02791072.2014.877322
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The Heffter Research Institute: Past and Hopeful Future

March 11, 2014 / Addiction, Anxiety disorders / PTSD, Mushrooms / Psilocybin, Other disciplines, Papers, Publications / By /

Abstract

This essay describes the founding of the Heffter Research Institute in 1993 and its development up to the present. The Institute is the only scientific research organization dedicated to scientific research into the medical value of psychedelics, and it has particularly focused on the use of psilocybin. The first clinical treatment study was of the value of psilocybin in obsessive-compulsive disorder. Next was a UCLA study of psilocybin to treat end-of-life distress in end-stage cancer patients. While that study was ongoing, a trial was started at Johns Hopkins University (JHU) to study the efficacy of psilocybin in treating anxiety and depression resulting from a cancer diagnosis. Following the successful completion of the UCLA project, a larger study was started at New York University, which is near completion. A pilot study of the value of psilocybin in treating alcoholism at the University of New Mexico also is nearing completion, with a larger two-site study being planned. Other studies underway involve the use of psilocybin in a smoking cessation program and a study of the effects of psilocybin in long-term meditators, both at JHU. The institute is now planning for a Phase 3 clinical trial of psilocybin to treat distress in end-stage cancer patients.

Nichols, D. E. (2014). The Heffter Research Institute: Past and Hopeful Future. Journal of Psychoactive Drugs, 46(1), 20–26. http://dx.doi.org/10.1080/02791072.2014.873688
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The entropic brain: a theory of conscious states informed by neuroimaging research with psychedelic drugs

February 3, 2014 / Consciousness, LSD, Mushrooms / Psilocybin, Neuroscience, Papers, Psychology, Psychopharmacology, Publications / By / , , , , , , ,

Abstract

Entropy is a dimensionless quantity that is used for measuring uncertainty about the state of a system but it can also imply physical qualities, where high entropy is synonymous with high disorder. Entropy is applied here in the context of states of consciousness and their associated neurodynamics, with a particular focus on the psychedelic state. The psychedelic state is considered an exemplar of a primitive or primary state of consciousness that preceded the development of modern, adult, human, normal waking consciousness. Based on neuroimaging data with psilocybin, a classic psychedelic drug, it is argued that the defining feature of “primary states” is elevated entropy in certain aspects of brain function, such as the repertoire of functional connectivity motifs that form and fragment across time. Indeed, since there is a greater repertoire of connectivity motifs in the psychedelic state than in normal waking consciousness, this implies that primary states may exhibit “criticality,” i.e., the property of being poised at a “critical” point in a transition zone between order and disorder where certain phenomena such as power-law scaling appear. Moreover, if primary states are critical, then this suggests that entropy is suppressed in normal waking consciousness, meaning that the brain operates just below criticality. It is argued that this entropy suppression furnishes normal waking consciousness with a constrained quality and associated metacognitive functions, including reality-testing and self-awareness. It is also proposed that entry into primary states depends on a collapse of the normally highly organized activity within the default-mode network (DMN) and a decoupling between the DMN and the medial temporal lobes (which are normally significantly coupled). These hypotheses can be tested by examining brain activity and associated cognition in other candidate primary states such as rapid eye movement (REM) sleep and early psychosis and comparing these with non-primary states such as normal waking consciousness and the anaesthetized state.

Carhart-Harris, R. L., Leech, R., Hellyer, P. J., Shanahan, M., Feilding, A., Tagliazucchi, E., Chialvo, D. R., & Nutt, D. (2014). The entropic brain: a theory of conscious states informed by neuroimaging research with psychedelic drugs. Frontiers in Human Neuroscience, 8, 1-22. http://dx.doi.org/10.3389/fnhum.2014.00020
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New study may explain magic mushrooms' effects

February 7, 2022 / Articles, Background articles, Mushrooms / Psilocybin, Research / By

New research by a group of mainly Britisch scientists, based on fMRI brain scans, has shown that the use of psilocybin (the active constituent of magic mushrooms) decreases the activity of certain parts of the brain in test subjects. Brain activity decreased especially in those parts that are involved in the managing and filtering of information.

This may explain why users often report that under the influence of magic mushrooms they experience impressions and feelings that were previously unnoticed. Logically, when the brain’s ability to filter and handle information is decreased, more information may reach our consciousness. This may also explain why users often report new insights after the use of magic mushrooms, sometimes having therapeutic effects.

Another indication for the therapeutic effects of magic mushrooms is that brain activity also decreased in the medial prefrontal cortex, a brain part that is often hyperactive in patients suffering from depression.

Remarkably, these new results confirm the ideas of Aldous Huxley (1894-1963). Huxley saw the brain as a ‘reducing valve’, filtering and making information more manageable for our consciousness. He posed that psychedelic drugs might decrease these reducing properties of the brain.

Click here for the abstract and a link to the full article.

14 May - Psychedelics & Psychosis with Phoebe Friesen, Dirk Corstens and Chelsea Rose

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