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Cees van Leeuwen

4 papers in the library · 229 citations · publishing 2014-2023

Papers

A phase 1/2 trial to assess safety and efficacy of a vaporized 5-methoxy-N,N-dimethyltryptamine formulation (GH001) in patients with treatment-resistant depression

Frontiers in Psychiatry June 20, 2023 Johannes T. Reckweg, Cees van Leeuwen, Cécile Henquet et al. 86 citations

In a small clinical trial with 16 adults suffering from treatment-resistant depression, an inhaled form of the psychedelic drug 5-MeO-DMT (GH001) was well tolerated and produced rapid antidepressant effects. An individualized dosing regimen of up to three increasing doses within a single day led to 87.5% of patients achieving remission (a depression score of 10 or less on the MADRS scale) by day 7, compared to 50% and 25% for single doses of 12 mg and 18 mg, respectively. Remission occurred as early as two hours after dosing for some patients. The findings suggest that individualized dosing may be more effective than a single dose.

The interplay of attention and consciousness in visual search, attentional blink and working memory consolidation.

Philosophical transactions of the Royal Society of London. Series B, Biological sciences May 5, 2014 Antonino Raffone, Narayanan Srinivasan, Cees van Leeuwen 85 citations

A unified neurocognitive theory, the theory of attention and consciousness (TAC), bridges separate accounts of consciousness and visual attention. TAC extends the global neuronal workspace model to a visual attentional workspace (VAW) controlled by executive routers, eliminating the need for explicit saliency maps. It explains phenomena including the attentional blink, working memory consolidation, illusory conjunctions, inattentional blindness, and working memory capacity. The theory proposes multiple processing stages between early visual representation and conscious access, suggests neural correlates of phenomenal consciousness, and reconciles all-or-none with graded views of conscious representation.

A Phase 1, Dose-Ranging Study to Assess Safety and Psychoactive Effects of a Vaporized 5-Methoxy-N, N-Dimethyltryptamine Formulation (GH001) in Healthy Volunteers.

Frontiers in Pharmacology January 1, 2021 Johannes T. Reckweg, Natasha L. Mason, Cees van Leeuwen et al. 58 citations

Vaporized 5-MeO-DMT (GH001) produces dose-dependent increases in psychedelic experience intensity in healthy volunteers, with individualized dose escalation yielding maximal effects on peak experience, mystical experience, ego dissolution, and altered states of consciousness. Higher single doses (6, 12, 18 mg) significantly increased ratings compared to 2 mg on all measures except challenging experiences. Cognition, mood, and well-being were unaffected. Vital signs remained stable, and adverse events were mild and self-resolving. Individualized dose escalation may be preferable for clinical applications aiming to maximize the psychedelic experience for therapeutic response.

System, subsystem, hive: boundary problems in computational theories of consciousness

Frontiers in Psychology October 4, 2016 Tomer Fekete, Cees van Leeuwen, Shimon Edelman

A computational measure of consciousness (MoC) must be graded, applicable across systems and times, but faces a boundary problem: any MoC that labels a system conscious will also label many of its subsystems, irrelevant extensions, and aggregates of conscious individuals as conscious, implying either that the measured properties are epiphenomenal or that minds proliferate bizarrely. The authors propose solving this by requiring MoCs to measure intrinsic or systemic properties—those that distinguish systems whose existence is a matter of fact from those existing only by interpretation. They argue that a systemic MoC resolves boundary issues and analyze Integrated Information Theory and Geometric Theory of consciousness as test cases.