"Similarities in psychedelic-induced visionary experiences and those produced by practices such as meditation and hypnosis and pathological conditions such as epilepsy indicate the need for a general model explaining visionary experiences."
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 thala...mic 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.
KEYWORDS: fMRI; functional connectivity; hallucinogens; psychedelics; thalamus
"Spaceflight severely impacts the human body. However, little is known about how gravity and gravitational alterations affect the human brain. Here, we aimed at measuring the effects of acute exposure to gravity transitions. We exposed 28 naïve participants to repetitive alterations between normal, hyper- and microgravity induced by a parabolic flight (PF) and measured functional MRI connectivity changes."
A few pictures from the Psychedelic Symposium 2017 in Copenhagen, featuring no less than four ALIUS researchers:
Christopher Timmermann on the dynamics of DMT experience & brain activity (video recording of the talk, starting at 1'57'00: https://www.facebook.com/psykedelisksamfund/videos/1903717876546181/)
Leor Roseman on psilocybin-assisted therapy (video recording of the talk, starting at 00'08'30': https://www.facebook.com/psykedelisksamfund/videos/1903824259868876/)...
Martin Fortier on the differences between psychedelics & deliriants (video recording of the talk, starting at 1'26'30: https://www.facebook.com/psykedelisksamfund/videos/1904271819824120/)
Raphaël Millière on the dynamic phenomenology of DMT-induced states (video recording of the talk, starting at 00'03'30: https://www.facebook.com/psykedelisksamfund/videos/1904422139809088/)
"All of the novel tryptamines interacted with 5-HT2A receptors and were partial or full 5-HT2A agonists. Binding affinity to the 5-HT2A receptor was lower for all of the tryptamines, including psilocin and DMT, compared with LSD and correlated with the reported psychoactive doses in humans. Several tryptamines, including psilocin, DMT, DiPT, 4-OH-DiPT, and 4-OH-MET, interacted with the serotonin transporter and partially the norepinephrine transporter, similar to 3,4-methylenedioxymethamphetamine but in contrast to LSD and mescaline. LSD but not the tryptamines interacted with adrenergic and dopaminergic receptors."
"In a large-scale (N = 1487) general population online study, we investigated the relationship between past experience with classic psychedelic substances (e.g. LSD, psilocybin, mescaline), nature relatedness, and ecological behavior (e.g. saving water, recycling). Using structural equation modeling we found that experience with classic psychedelics uniquely predicted self-reported engagement in pro-environmental behaviors"
Part 2 of Raphaël Millière's interview for The Consciousness Podcast is online. In this episode he discusses the following topics:
• What drug-induced ego dissolution can tell us about the brain's self-model.
• Insights on the phenomenology of DMT from interview data as part of his collaboration with ALIUS researchers Christopher Timmermann and Leor Roseman.
• What states induced by meditation and psychedelic drugs might have in commun.
• His ongoing data mining study of Erowid.org (in collaboration with Hannes Kettner), which extracts themes from thousands of narrative reports of drug-induced experiences.
"The state of consciousness induced by N,N-dimethyltryptamine (DMT) is one of the most extraordinary of any naturally-occurring psychedelic substance. Users consistently report the complete replacement of normal subjective experience with a novel “alternate universe,” often densely populated with a variety of strange objects and other highly complex visual content, including what appear to be sentient “beings.” The phenomenology of the DMT state is of great interest to psycho...logy and calls for rigorous academic enquiry. The extremely short duration of DMT effects—less than 20 min—militates against single dose administration as the ideal model for such enquiry. Using pharmacokinetic modeling and DMT blood sampling data, we demonstrate that the unique pharmacological characteristics of DMT, which also include a rapid onset and lack of acute tolerance to its subjective effects, make it amenable to administration by target-controlled intravenous infusion. This is a technology developed to maintain a stable brain concentration of anesthetic drugs during surgery. Simulations of our model demonstrate that this approach will allow research subjects to be induced into a stable and prolonged DMT experience, making it possible to carefully observe its psychological contents, and provide more extensive accounts for subsequent analyses. This model would also be valuable in performing functional neuroimaging, where subjects are required to remain under the influence of the drug for extended periods. Finally, target-controlled intravenous infusion of DMT may aid the development of unique psychotherapeutic applications of this psychedelic agent."
Journée d’étude organisée par David Dupuis et Maddalena Canna
(3 Octobre 2017, au Collège de France - Salle 2, 11 place Marcelin Berthelot - 75005 Paris)
Entrée libre sans inscription
"One of the most challenging questions regarding the nature and neural basis of consciousness is the embodied dimension of the phenomenon, that is, feeling located within the body and viewing the world from that spatial perspective. Current theories in neurophysiology highlight the active role of multisensory and sensorimotor integration in supporting self-location and self-perspective, and propose the right temporal-parietal-junction (rTPJ) as a key area for such function. T...hese theories are based mainly on findings from two experimental paradigms: manipulation of bottom-up multisensory information integration regarding one’s body location (full-body illusion), or direct and invasive manipulation disrupting brain activity at the rTPJ. In this study we take a different approach by using hypnotic suggestion – a non-invasive top-down technique – to manipulate the subjective experience of self-location. The brain activity of 18 right-handed participants was recorded using magnetoencephalography (MEG) while their subjective experience of self-location was hypnotically manipulated. Spectral analyses were conducted on the spontaneous MEG data before and during an induction of an out-of-body experience by a trained psychiatrist. The results indicate high correlations between power at alpha and high-gamma frequency-bands and the degree of perceived change in self-location. Regions exhibiting such correlations include temporal-occipital regions, the right TPJ, as well as frontal and midline regions. These findings are in line with an oscillatory-based predictive coding framework."
Carhart-Harris' latest paper:
"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 [...]: 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)."
Martin Fortier discussing psychedelics, deliriants, and the naturalistic approach to altered states of consciousness