Author Correction: Psilocybin enhances insightfulness in meditation: a perspective on the global topology of brain imaging during meditation
Scientific Reports April 23, 2024 Berit Singer, Daniel Meling, Matthias Hirsch-Hoffmann et al.
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Milan Scheidegger
ZHAW Zurich University of Applied Sciences, University of Zurich
55 papers in the library · 2,066 citations · publishing 2011-2026
Papers
Pharmacokinetic and Pharmacodynamic Interaction of the Ayahuasca Constituents Harmine and Dimethyltryptamine (DMT) in the Rat Brain
January 4, 2023 Klemens Egger, Frederik Gudmundsen, Naja Støckel Jessen et al. preprint
Co-administration of harmine with N,N-dimethyltryptamine (DMT) in rats inhibited the formation of the DMT metabolite indole-3-acetic acid in the brain and increased cerebral availability of DMT, confirming harmine's role in making oral DMT bioavailable. However, no significant occupancy by DMT at serotonin 5-HT2A receptors was detected ex vivo, despite brain DMT concentrations reaching 11.3 µM at moderate doses. Low doses of DMT and/or harmine did not strongly influence brain glucose metabolism measured with [18F]FDG-PET. The results call for further experiments on dose-dependent effects of harmine/DMT on receptor occupancy and cerebral metabolism.
Acute ketamine administration modulates glutamatergic neurotransmission and functional brain activation in prefrontal cortex implications for major depression
Pharmacopsychiatry September 1, 2011 Milan Scheidegger, A Henning, Martin Walter et al.
A subanaesthetic dose of ketamine alters brain activity during emotional processing and increases glutamate-glutamine cycling in the pregenual anterior cingulate cortex, a region linked to mood regulation. In 23 healthy subjects, ketamine infusion changed fMRI responses to emotional pictures, and these changes correlated with shifts in glutamine-to-glutamate ratios measured by spectroscopy. The findings suggest ketamine's rapid antidepressant effect may stem from enhanced glutamatergic neurotransmission.
Emotionalcognitive processing and brain metabolism after pharmacological challenge with ketamine
Pharmacopsychiatry September 1, 2011 Simone Grimm, Milan Scheidegger, A Henning et al.
Ketamine, a glutamatergic NMDA receptor antagonist with rapid antidepressant properties, was used to investigate the neurobiology of major depressive disorder. In a multimodal imaging study of 23 healthy subjects, a single ketamine infusion increased negative BOLD responses in brain regions involved in emotional processing, particularly limbic areas linked to emotional information and higher-order mental functions. During cognitive processing, ketamine affected negative BOLD responses in anterior but not posterior regions of the default-mode network. Strong correlations were found between glutamate, glutamine, GABA, and glutamine/glutamate ratios and these brain responses after ketamine administration, suggesting a link to glutamatergic neurotransmission.
Meditation, Psychedelics, and Brain Connectivity: A Randomised Controlled Resting-State fMRI Study of N,N -Dimethyltryptamine and Harmine in a Meditation Retreat
medRxiv Klemens Egger, Daniel Meling, Firuze Polat et al. preprint
In a double-blind, placebo-controlled pharmaco-fMRI study, 40 meditation practitioners on a three-day retreat received either placebo or buccal DMT-harmine (120 mg each). Meditation alone increased network segregation across several resting-state networks, while DMT-harmine increased functional connectivity within the visual network and between visual and attention networks. Between-group differences showed increased connectivity between visual and salience networks in the DMT-harmine group. No prolonged cortical gradient disruption was observed, indicating a return to typical brain organization shortly after the experience. Meditation reduced connectivity between networks, whereas DMT-harmine increased within- and between-network connectivity, revealing distinct neural mechanisms.