OPEN Foundation

Menu
Search
Close this search box.

Neuroscience

Increased thalamic resting-state connectivity as a core driver of LSD-induced hallucinations

September 21, 2017 / LSD, Neuroscience, Papers, Publications / By / , , , , , ,

Abstract

OBJECTIVE:
It has been proposed that the thalamocortical system is an important site of action of hallucinogenic drugs and an essential component of the neural correlates of consciousness. Hallucinogenic drugs such as LSD can be used to induce profoundly altered states of consciousness, and it is thus of interest to test the effects of these drugs on this system.
METHOD:
100 μg LSD was administrated orally to 20 healthy participants prior to fMRI assessment. Whole brain thalamic functional connectivity was measured using ROI-to-ROI and ROI-to-voxel approaches. Correlation analyses were used to explore relationships between thalamic connectivity to regions involved in auditory and visual hallucinations and subjective ratings on auditory and visual drug effects.
RESULTS:
LSD caused significant alterations in all dimensions of the 5D-ASC scale and significantly increased thalamic functional connectivity to various cortical regions. Furthermore, LSD-induced functional connectivity measures between the thalamus and the right fusiform gyrus and insula correlated significantly with subjective auditory and visual drug effects.
CONCLUSION:
Hallucinogenic drug effects might be provoked by facilitations of cortical excitability via thalamocortical interactions. Our findings have implications for the understanding of the mechanism of action of hallucinogenic drugs and provide further insight into the role of the 5-HT2A -receptor in altered states of consciousness.
Mueller, F., Lenz, C., Dolder, P., Lang, U., Schmidt, A., Liechti, M., & Borgwardt, S. (2017). Increased thalamic resting‐state connectivity as a core driver of LSD‐induced hallucinations. Acta Psychiatrica Scandinavica. 10.1111/acps.12818
Link to full text

Assessing the psychedelic “after-glow” in ayahuasca users: post-acute neurometabolic and functional connectivity changes are associated with enhanced mindfulness capacities

September 1, 2017 / Ayahuasca, Depressive Disorders, Neuroscience, Papers, Psychology, Publications / By / , , , , , ,

Abstract

BACKGROUND:
Ayahuasca is a plant tea containing the psychedelic 5-HT2A agonist N,N-dimethyltryptamine and harmala monoamine-oxidase inhibitors. Acute administration leads to neurophysiological modifications in brain regions of the default mode network, purportedly through a glutamatergic mechanism. Post-acutely, ayahuasca potentiates mindfulness capacities in volunteers and induces rapid and sustained antidepressant effects in treatment-resistant patients. However, the mechanisms underlying these fast and maintained effects are poorly understood. Here, we investigated in an open-label uncontrolled study in 16 healthy volunteers ayahuasca-induced post-acute neurometabolic and connectivity modifications and their association with mindfulness measures.
METHODS:
Using 1H-magnetic resonance spectroscopy and functional connectivity, we compared baseline and post-acute neurometabolites and seed-to-voxel connectivity in the posterior and anterior cingulate cortex after a single ayahuasca dose.
RESULTS:
Magnetic resonance spectroscopy showed post-acute reductions in glutamate+glutamine, creatine, and N-acetylaspartate+N-acetylaspartylglutamate in the posterior cingulate cortex. Connectivity was increased between the posterior cingulate cortex and the anterior cingulate cortex, and between the anterior cingulate cortex and limbic structures in the right medial temporal lobe. Glutamate+glutamine reductions correlated with increases in the “nonjudging” subscale of the Five Facets Mindfulness Questionnaire. Increased anterior cingulate cortex-medial temporal lobe connectivity correlated with increased scores on the self-compassion questionnaire. Post-acute neural changes predicted sustained elevations in nonjudging 2 months later.
CONCLUSIONS:
These results support the involvement of glutamate neurotransmission in the effects of psychedelics in humans. They further suggest that neurometabolic changes in the posterior cingulate cortex, a key region within the default mode network, and increased connectivity between the anterior cingulate cortex and medial temporal lobe structures involved in emotion and memory potentially underlie the post-acute psychological effects of ayahuasca.
Sampedro, F., de la Fuente Revenga, M., Valle, M., Roberto, N., Domínguez-Clavé, E., Elices, M., … & Friedlander, P. (2017). Assessing the psychedelic “after-glow” in ayahuasca users: post-acute neurometabolic and functional connectivity changes are associated with enhanced mindfulness capacities. International Journal of Neuropsychopharmacology. 10.1093/ijnp/pyx036
Link to full text

Assessing the psychedelic "after-glow" in ayahuasca users: post-acute neurometabolic and functional connectivity changes are associated with enhanced mindfulness capacities

October 24, 2021 / Ayahuasca, Depressive Disorders, Neuroscience, Papers, Psychology, Publications / By / , , , , , ,

Abstract

Background:

Ayahuasca is a plant tea containing the psychedelic 5-HT2A agonist N,N-dimethyltryptamine and harmala monoamine-oxidase inhibitors. Acute administration leads to neurophysiological modifications in brain regions of the default mode network, purportedly through a glutamatergic mechanism. Post-acutely, ayahuasca potentiates mindfulness capacities in volunteers and induces rapid and sustained antidepressant effects in treatment-resistant patients. However, the mechanisms underlying these fast and maintained effects are poorly understood. Here, we investigated in an open-label uncontrolled study in 16 healthy volunteers ayahuasca-induced post-acute neurometabolic and connectivity modifications and their association with mindfulness measures.

Methods:

Using 1H-magnetic resonance spectroscopy and functional connectivity, we compared baseline and post-acute neurometabolites and seed-to-voxel connectivity in the posterior and anterior cingulate cortex after a single ayahuasca dose.

Results:

Magnetic resonance spectroscopy showed post-acute reductions in glutamate+glutamine, creatine, and N-acetylaspartate+N-acetylaspartylglutamate in the posterior cingulate cortex. Connectivity was increased between the posterior cingulate cortex and the anterior cingulate cortex, and between the anterior cingulate cortex and limbic structures in the right medial temporal lobe. Glutamate+glutamine reductions correlated with increases in the “nonjudging” subscale of the Five Facets Mindfulness Questionnaire. Increased anterior cingulate cortex-medial temporal lobe connectivity correlated with increased scores on the self-compassion questionnaire. Post-acute neural changes predicted sustained elevations in nonjudging 2 months later.

Conclusions:

These results support the involvement of glutamate neurotransmission in the effects of psychedelics in humans. They further suggest that neurometabolic changes in the posterior cingulate cortex, a key region within the default mode network, and increased connectivity between the anterior cingulate cortex and medial temporal lobe structures involved in emotion and memory potentially underlie the post-acute psychological effects of ayahuasca. Sampedro, F., de la Fuente Revenga, M., Valle, M., Roberto, N., Domínguez-Clavé, E., Elices, M., … & Friedlander, P. (2017). Assessing the psychedelic “after-glow” in ayahuasca users: post-acute neurometabolic and functional connectivity changes are associated with enhanced mindfulness capacities. International Journal of Neuropsychopharmacology. 10.1093/ijnp/pyx036

Serotonin and brain function: a tale of two receptors

August 31, 2017 / Neuroscience, Papers, Psychology, Publications / By / ,

Abstract

Previous attempts to identify a unified theory of brain serotonin function have largely failed to achieve consensus. In this present synthesis, we integrate previous perspectives with new and older data to create a novel bipartite model centred on the view that serotonin neurotransmission enhances two distinct adaptive responses to adversity, mediated in large part by its two most prevalent and researched brain receptors: the 5-HT1A and 5-HT2A receptors. We propose that passive coping (i.e. tolerating a source of stress) is mediated by postsynaptic 5-HT1AR signalling and characterised by stress moderation. Conversely, we argue that active coping (i.e. actively addressing a source of stress) is mediated by 5-HT2AR signalling and characterised by enhanced plasticity (defined as capacity for change). We propose that 5-HT1AR-mediated stress moderation may be the brain’s default response to adversity but that an improved ability to change one’s situation and/or relationship to it via 5-HT2AR-mediated plasticity may also be important – and increasingly so as the level of adversity reaches a critical point. We propose that the 5-HT1AR pathway is enhanced by conventional 5-HT reuptake blocking antidepressants such as the selective serotonin reuptake inhibitors (SSRIs), whereas the 5-HT2AR pathway is enhanced by 5-HT2AR-agonist psychedelics. This bipartite model purports to explain how different drugs (SSRIs and psychedelics) that modulate the serotonergic system in different ways, can achieve complementary adaptive and potentially therapeutic outcomes.
Carhart-Harris, R. L., & Nutt, D. J. (2017). Serotonin and brain function: a tale of two receptors. Journal of Psychopharmacology (Oxford, England), 31(9), 1091. 10.1177/0269881117725915
Link to full text

Synaptic Loss and the Pathophysiology of PTSD: Implications for Ketamine as a Prototype Novel Therapeutic

August 26, 2017 / Anxiety Disorders / PTSD, Ketamine, Neuroscience, Papers, Psychology, Publications / By / , , , , , ,

Abstract

PURPOSE OF REVIEW:
Studies of the neurobiology and treatment of PTSD have highlighted many aspects of the pathophysiology of this disorder that might be relevant to treatment. The purpose of this review is to highlight the potential clinical importance of an often-neglected consequence of stress models in animals that may be relevant to PTSD: the stress-related loss of synaptic connectivity.
RECENT FINDINGS:
Here, we will briefly review evidence that PTSD might be a “synaptic disconnection syndrome” and highlight the importance of this perspective for the emerging therapeutic application of ketamine as a potential rapid-acting treatment for this disorder that may work, in part, by restoring synaptic connectivity. Synaptic disconnection may contribute to the profile of PTSD symptoms that may be targeted by novel pharmacotherapeutics.
Krystal, J. H., Abdallah, C. G., Averill, L. A., Kelmendi, B., Harpaz-Rotem, I., Sanacora, G., … & Duman, R. S. (2017). Synaptic loss and the pathophysiology of PTSD: implications for ketamine as a prototype novel therapeutic. Current Psychiatry Reports, 19(10), 74. 10.1007/s11920-017-0829-z
Link to full text

Interactions of Hallucinogens with the Glutamatergic System: Permissive Network Effects Mediated Through Cortical Layer V Pyramidal Neurons

August 23, 2017 / LSD, Mushrooms / Psilocybin, Neuroscience, Papers, Publications / By /

Abstract

Recordings made from layer V (L5) pyramidal cells of the prefrontal cortex (PFC) and neocortex in rodent slice preparations have shown that serotonin (5-hydroxytryptamine, 5-HT) and serotonergic hallucinogens induce an increase in the frequency of spontaneous excitatory postsynaptic currents (EPSCs) in the apical dendritic field by activating 5-HT2A receptors. Serotonergic hallucinogens induce late EPSCs and increase recurrent network activity when subcortical or mid-cortical regions are stimulated at low frequencies (e.g., 0.1 Hz). A range of agonists or positive allosteric modulators (PAMs) for mostly Gi/o-coupled receptors, including metabotropic glutamate2 (mGlu2), adenosine A1, or μ-opioid receptors, suppress these effects of 5-HT2A receptor stimulation. Furthermore, a range of mostly Gq/11-coupled receptors (including orexin2 [OX2]; α1-adrenergic, and mGlu5 receptors) similarly induce glutamate (Glu) release onto L5 pyramidal cells. Evidence implicates a number of brain regions in mediating these effects of serotonergic hallucinogens and Gq/11-coupled receptors including the midline and intralaminar thalamic nuclei, claustrum, and neurons in deep PFC. These effects on 5-HT2Areceptors and related GPCRs appear to play a major role in the behavioral effects of serotonergic hallucinogens, such as head twitches in rodents and higher order behaviors such as rodent lever pressing on the differential-reinforcement-of-low rate 72-s (DRL 72-s) schedule. This implies that the effects of 5-HT2A receptor activation on the activity of L5 pyramidal cells may be responsible for mediating a range of behaviors linked to limbic circuitry with connectivity between the PFC, striatum, thalamus, claustrum, striatum, amygdala, and the hippocampal formation.

Marek, G. J. (2017). Interactions of Hallucinogens with the Glutamatergic System: Permissive Network Effects Mediated Through Cortical Layer V Pyramidal Neurons. 10.1007/7854_2017_480
Link to full text

The Non-Peptide Arginine-Vasopressin v1a Selective Receptor Antagonist, SR49059, Blocks the Rewarding, Prosocial, and Anxiolytic Effects of 3,4-Methylenedioxymethamphetamine and Its Derivatives in Zebra Fish

August 14, 2017 / MDMA, Neuroscience, Papers, Psychology, Publications / By / , , ,

Abstract

3,4-Methylenedioxymethamphetamine (MDMA) and its derivatives, 2,5-dimethoxy-4-bromo-amphetamine hydrobromide (DOB) and para-methoxyamphetamine (PMA), are recreational drugs whose pharmacological effects have recently been attributed to serotonin 5HT2A/C receptors. However, there is growing evidence that the oxytocin (OT)/vasopressin system can modulate some the effects of MDMA. In this study, MDMA (2.5–10 mg/kg), DOB (0.5 mg/kg), or PMA (0.005, 0.1, or 0.25 mg/kg) were administered intramuscularly to adult zebra fish, alone or in combination with the V1a vasopressin antagonist, SR49059 (0.01–1 ng/kg), before carrying out conditioned place preference (CPP), social preference, novel tank diving, and light–dark tests in order to evaluate subsequent rewarding, social, and emotional-like behavior. The combination of SR49059 and each drug progressively blocked: (1) rewarding behavior as measured by CPP in terms of time spent in drug-paired compartment; (2) prosocial effects measured on the basis of the time spent in the proximity of a nacre fish picture; and (3) anxiolytic effects in terms of the time spent in the upper half of the novel tank and in the white compartment of the tank used for the light–dark test. Antagonism was obtained at SR49059 doses which, when given alone, did not change motor function. In comparison with a control group, receiving vehicle alone, there was a three to five times increase in the brain release of isotocin (the analog of OT in fish) after treatment with the most active doses of MDMA (10 mg/kg), DOB (0.5 mg/kg), and PMA (0.1 mg/kg) as evaluated by means of bioanalytical reversed-phase high-performance liquid chromatography. Taken together, these findings show that the OT/vasopressin system is involved in the rewarding, prosocial, and anxiolytic effects of MDMA, DOB, and PMA in zebra fish and underline the association between this system and the behavioral alterations associated with disorders related to substance abuse.
Ponzoni, L., Braida, D., Bondiolotti, G., & Sala, M. (2017). The Non-Peptide Arginine-Vasopressin v1a Selective Receptor Antagonist, SR49059, Blocks the Rewarding, Prosocial, and Anxiolytic Effects of 3, 4-Methylenedioxymethamphetamine and Its Derivatives in Zebra Fish. Frontiers in psychiatry, 8, 146. 10.3389/fpsyt.2017.00146
Link to full text

Shannon entropy of brain functional complex networks under the influence of the psychedelic Ayahuasca

August 7, 2017 / Ayahuasca, Neuroscience, Papers, Psychology, Publications / By / , , , ,

Abstract

The entropic brain hypothesis holds that the key facts concerning psychedelics are partially explained in terms of increased entropy of the brain’s functional connectivity. Ayahuasca is a psychedelic beverage of Amazonian indigenous origin with legal status in Brazil in religious and scientific settings. In this context, we use tools and concepts from the theory of complex networks to analyze resting state fMRI data of the brains of human subjects under two distinct conditions: (i) under ordinary waking state and (ii) in an altered state of consciousness induced by ingestion of Ayahuasca. We report an increase in the Shannon entropy of the degree distribution of the networks subsequent to Ayahuasca ingestion. We also find increased local and decreased global network integration. Our results are broadly consistent with the entropic brain hypothesis. Finally, we discuss our findings in the context of descriptions of “mind-expansion” frequently seen in self-reports of users of psychedelic drugs.
Viol, A., Palhano-Fontes, F., Onias, H., de Araujo, D. B., & Viswanathan, G. M. (2016). Shannon entropy of brain functional complex networks under the influence of the psychedelic Ayahuasca. arXiv preprint arXiv:1611.00358. 10.1038/s41598-017-06854-0
Link to full text

A Systematic Review Of Research On N,N-Dimethyltryptamine

August 1, 2017 / DMT, Neuroscience, Papers, Psychology / By / ,

Abstract

Introduction: The effects of the endogenous hallucinogen N,N-dimethyltryptamine are poorly understood and its medical significance is widely unknown. A small number of  studies regarding its biochemical, pharmaceutical and physiological role have been conducted and the efficacy of its therapeutic potential is presently disregarded. How can scientists proceed in gaining insight into DMT and discovering possible medical uses of this substance?
Materials and Methods: Published articles from  1964 to the present year have been reviewed and the outcome of the studies summarized. The results of drug action,  therapeutic use and potential were investigated . Studies that appeared to have little medical purpose or those, which focus on the use of  Ayahuasca, a South American ritual drink containing N,N-dimethyltryptamine and a monoamine oxidase (MAO)  inhibitor of plant origin, have been excluded.
Results: The research conducted between 1964 and 1987 seems to be an approach to understanding general chemical and biochemical properties of the substance (e.g. metabolites, tolerance, distribution, toxicity, etc.). Rick Strassman, who conducted a broad study from 1990 till 1994 has initiated a recurring interest in the field of psychopharmacology towards DMT. Thus, in the following years, the research was focused on the therapeutic gain of N,N-dimethyltryptamine but resulted mostly inconclusively leading to suggestions of further research. The findings have shown contradictions of already established knowledge, especially for receptors like the sigma-1 receptor, the only direct agonist of which is found to be N,N-dimethyltryptamie.
Conclusion: The studies that now need to be conducted should analyze the correlations between psychiatric diseases (e.g. schizophrenia), purpose of the normal endogenous production and exact action, and the already suggested in various studies therapeutic importance. The low amount of knowledge about the drug action (in case of pharmaceutical use), its targets and drug effect should motivate researchers to gain more insight.
Hristova, D., & Zhelyazkova-Savova, M. (2017). A SYSTEMATIC REVIEW OF RESEARCH ON N, N-DIMETHYLTRYPTAMINE. Scripta Scientifica Vox Studentium, 1(1).
Link to full text

The 2017 Ayahuasca Technical Report

July 26, 2017 / Anthropology & Sociology, Anxiety Disorders / PTSD, Ayahuasca, Biology & Ethnobotany, Neuroscience, Papers, Psychiatry & Medicine, Psychology, Publications, Substance Use Disorder / By

ICEERS has just released the 2017 edition of the Ayahuasca Technical Report. Signed by ten of the world’s leading ayahuasca researchers, this report is an important document that summarizes the most relevant scientific findings from the past few decades, as well as key information about the history, legality, pharmacology, and potential therapeutic or adverse effects of ayahuasca. Our intention with this report is to provide objective and up-to-date information to policy makers, judges, lawyers and other officials in charge of developing policies, programs, legislation or involved in legal cases relating to ayahuasca.
Link to full text

interested in becoming a trained psychedelic-assisted therapist?

Management of Psychedelic-Related Complications - Online Event - Nov 20th

REGISTER NOW