Medical Hypotheses
January 1, 1990
Karl Jansen
96 citations
The near-death experience (NDE) is a dissociative mental state with characteristic features that can be reproduced by ketamine, which acts at sigma sites and blocks NMDA-linked PCP receptors to reduce ischemic damage. Endogenous ligands, alpha and beta-endopsychosin, have been detected for these receptors, suggesting an explanation for some NDEs: the endopsychosins may be released in abnormal quantity to protect neurons from ischemic and other excitotoxic damage, and the NDE is a side effect on consciousness with important psychological functions.
Medical Hypotheses
April 11, 2015
Enrico Facco, Christian Agrillo, Bruce Greyson
61 citations
Near-death experiences (NDEs) are deep, universal altered states of consciousness with clear phenomenology and incidence, whose features challenge the dominant mechanist-reductionist view of mind as a byproduct of brain circuitry. This paradigm originated from Descartes' separation of mind and matter and the historical conflict between science and the Inquisition, which removed subjective mental properties from scientific inquiry. Twentieth-century physics moved beyond this classical paradigm, renewing scientific interest in mind. Modern NDE research has reopened debate on the mind-brain relationship and consciousness. The authors argue it is time to reappraise scientific interpretations of NDEs, their relationship with other altered states, and the concept of altered state itself, which appears ill-founded, suggesting a need for revision of conventional approaches to subjective phenomena and reflection on links between non-ordinary mental expressions.
Medical Hypotheses
July 6, 2013
Sérgio Mota-Rolim, John Fontenele Araújo
50 citations
Lucid dreaming—being aware of dreaming during rapid eye movement (REM) sleep—may be linked to increased frontal lobe activity, contrasting with psychosis, which involves reduced frontal activity and dream-like features intruding into wakefulness. The authors propose that frontal brain stimulation during REM sleep could trigger lucid dreams, offering a test of this hypothesis. They suggest lucid dreaming research could advance understanding of consciousness and its disorders, serve as therapy for recurrent nightmares in depression and PTSD, and aid physical rehabilitation through motor imagery during dreams.
Medical Hypotheses
January 1, 2006
U Maas, S Strubelt
41 citations
Ibogaine, the main alkaloid of the Central African Iboga shrub, is used in Gabonian initiation ceremonies to induce near-death experiences and in Western clinics for addiction treatment, but it is illegal in the US and most of Europe because at least eight people have died after taking it, often days later or from very small doses. The authors hypothesize that these deaths result from cardiac arrhythmias caused by autonomic nervous system dysregulation. Small doses stimulate the sympathetic system (fight or flight), while high doses cause vagal dominance (feigned death).
Medical Hypotheses
February 11, 2019
K.p.c. Kuypers
34 citations
Psychedelic substances show promise for treating stress-related disorders, with effects that can persist after a single dose. Even low, micro-doses that do not alter consciousness may improve cognitive processes and well-being. The neurobiological mechanisms behind these lasting effects remain unclear. While prior research focused on the central nervous system, immune system, and neuroendocrine system, a central role is proposed for sleep and the microbiome in the effects of regular and low doses of psychedelics, respectively. The hypothesis is explained and studies to test it are suggested. A holistic approach is needed, incorporating all affected biological processes and factors like route of administration, form, diet, and lifestyle.
Medical Hypotheses
November 1, 2020
Michael Raduga, Oleg Kuyava, Natalia Sevcenko
31 citations
During REM sleep, people normally dream, but some also experience lucid dreaming (being conscious during a dream), false awakening (dreaming that one has woken up), sleep paralysis (temporary muscle atonia upon waking or falling asleep), and out-of-body experiences (the sensation of leaving the physical body). A survey of 974 people on the streets of Moscow found that 88% had experienced at least one of these phenomena, and 43% experienced one often. These phenomena were closely correlated with each other, and their recurrence correlated with sleep duration and dream recall frequency. The results suggest these REM sleep dissociative phenomena are interconnected.
Medical Hypotheses
January 1, 2021
Timothy D Brewerton, Adele Lafrance, Michael C Mithoefer
28 citations
Eating disorders remain difficult to treat, especially when accompanied by posttraumatic stress disorder. MDMA-assisted psychotherapy for treatment-resistant PTSD shows promise, with two-thirds of participants achieving full remission at one year or more follow-up. The authors hypothesize this therapy will be effective for both eating disorder and PTSD symptoms in people with both conditions. MDMA's effects—reduced fear, enhanced wellbeing, increased sociability, reduced self-criticism, increased compassion, interpersonal trust, and alert consciousness—may counteract avoidance and hyperarousal in therapy. Other features like body image distortion, cognitive rigidity, and socio-emotional difficulties may also improve. Personal accounts describe benefit, but risks and challenges are noted.
Medical Hypotheses
September 24, 2019
Christopher B. Germann
20 citations
A new hypothesis proposes that controlled psilocybin interventions can positively impact leucocyte telomere length, a predictor of mortality and aging-related diseases. The argument draws on evidence that psilocybin improves mental health conditions such as depression, anxiety, PTSD, OCD, and addiction, and that better mental health correlates with longer telomeres. Meditative states of consciousness, which share neurophysiological and phenomenological features with psilocybin-induced states, also benefit genetic aging. A single psilocybin dose can produce transformative experiences rated among the five most meaningful life events by about 70% of healthy volunteers. The hypothesis suggests these profound psychological events leave molecular genetic or epigenetic marks. Quantitative telomere analysis is proposed as an adjunctive biological marker in future psilocybin studies to facilitate scientific consilience.
Medical Hypotheses
March 11, 2020
J S Torday
16 citations
Consciousness is proposed to be a product of the Singularity/Big Bang, arising from the internalization of environmental factors that shaped human physiology. This view requires that consciousness diachronically cuts across space-time and operates on the same data system as cosmology. By recognizing this mechanistic interrelationship, humans can transcend individual consciousness and approach a universal Consciousness by authoring their own software. The hypothesis argues that previous explanations, from Plato to Descartes and Chalmers, lack empirical evidence for what consciousness actually constitutes.
Medical Hypotheses
September 1, 2019
Enrico Facco, Laura Mendozzi, Angelo Bona et al.
16 citations
Five individuals with unusual hypnotic ability, free of psychiatric disorders, spontaneously experienced multiple identities during hypnosis, which they later did not recall due to post-hypnotic amnesia. Brain scans showed reduced connectivity in the Default Mode Network, particularly between the posterior cingulate cortex and medial prefrontal cortex. Comparing these findings with fMRI data from Dissociative Identity Disorder patients suggests a continuum between normal mental functioning, where multiple identities can coexist unconsciously, and pathological dissociation. The authors argue that a sharp boundary between normal and pathological experiences may be artificial, and that non-ordinary mental expressions like these should be understood rather than treated.
Medical Hypotheses
March 23, 2018
K.p.c. Kuypers
16 citations
Creativity involves both flexible divergent thinking and rigid convergent thinking. Psychedelic drugs such as psilocybin can enhance creativity and influence mood, empathy, and openness to experience. Flexible thinking is impaired in anxiety disorders and depression, and preliminary evidence suggests psychedelics may help treat these conditions. The neurobiological mechanisms by which psychedelics enhance flexible thinking remain unknown. A model is proposed that integrates neuronal networks, neurotransmitters, and personal factors, which can be tested through placebo-controlled pharmaco-imaging studies in healthy volunteers.
Medical Hypotheses
January 1, 2007
Bruce G Charlton
15 citations
Alienation, the feeling that life is meaningless and that we do not belong, is not inevitable. Animistic thinking, which regards significant entities as sentient agents with minds, is the natural and spontaneous human worldview, shared by children and hunter-gatherers. This thinking embeds humans in a world of social relationships with animals, plants, and landscapes. Formal education overwrites animism with rationalistic objectivity, creating alienation by estranging people from a relational world. Recovering animistic thinking involves detachment from social systems that enforce objectivity—through solitude, leisure, nature contact, or altered states of consciousness such as meditation, lucid dreaming, trance states, or intoxication. Intoxication, however, impairs memory and can be dangerous, yet seeking altered states remains a major spiritual practice.
Medical Hypotheses
March 27, 2023
Emma Peters, Sanne Golembiewski, Daniel Erlacher et al.
12 citations
Lucid dreaming—becoming aware of a dream while asleep—can be used to practice motor skills, potentially improving real-world performance. The brain generates an immersive, VR-like environment with realistic body sensations during lucid dreams. Experimental studies show promising performance gains after lucid dreaming motor practice, with similarities in brain activity, eye movements, muscle activity, and autonomic responses to physical practice. Surveys indicate athletes already incorporate lucid dreaming into training. Placebo effects and increased motivation after practice need further investigation. Challenges such as the rarity of lucid dreams, lack of proper training, and limited control over dream content must be addressed to strengthen this approach for broader use.
Medical Hypotheses
December 1, 2008
Bruce G Charlton
12 citations
Genetic engineering could be used to enhance human spiritual and religious experiences, a concept termed 'genospirituality'. If technologies safely engineer genes linked to spiritual behaviors, people might choose their degree of religiosity, potentially increasing direct religious experiences like revelation, animistic thinking where natural features are seen as sentient, or shamanistic states of altered consciousness that can be self-induced and switched off. Trade-offs may include reduced drive for status and monetary rewards, but also more altruistic, moral behaviors and strengthened communal joy. Genospirituality would likely appeal to those unable to achieve desired spiritual experiences.
Medical Hypotheses
July 15, 2009
Peter Kovacic
10 citations
No Summary
Medical Hypotheses
February 1, 2016
Thomas S. Ray
6 citations
MDMA (ecstasy) produces a distinct open-hearted mental state that defines the drug class 'entactogens'. While consensus holds that this state arises from neurotransmitter release, primarily serotonin, an alternative hypothesis proposes simultaneous direct activation of imidazoline-1 (I1) and serotonin-2 (5-HT2) receptors. This hypothesis is grounded in 'mental organ' theory, where mental organs are neuron populations expressing a defining metabotropic receptor, each playing an evolutionarily shaped role in the mind. For a mental organ to enter consciousness, it must be directly activated at its receptor, 5-HT2 must be co-activated, and 5-HT2 activation loads the organ into consciousness.
Medical Hypotheses
January 1, 1986
T Riedlinger, J Riedlinger
5 citations
Birth trauma theories, particularly Stanislav Grof's, have been dismissed by mainstream psychology due to lack of evidence and assumptions about neonatal brain development. However, evidence from over 3,500 psychedelic-assisted psychotherapy sessions suggests a link between unconscious birth trauma memories and mental conditions. Research on psychedelic effects, subcortical learning, and emotional response offers explanations that address Freud's objections without refuting them. This review concludes that birth trauma theories deserve more serious consideration from mainstream psychologists and medical researchers.
Medical Hypotheses
March 1, 2017
Grzegorz R Juszczak
4 citations
LSD, a model psychedelic, triggers sensory experiences such as illusory movement, floating, merging with surroundings, and out-of-body experiences. While the molecular action at 5-HT2a receptors is known, how these lead to specific sensations is unclear. The authors propose that LSD disrupts the integration of sensory input with information about the body's movement, as serotonergic neurons normally convey motor activity and orienting responses. This disruption results in the perception of illusory movement attributed to the self or external objects.
Medical Hypotheses
November 1, 2013
E Maciejczyk, P Kafarski
4 citations
Mannitol, abundant in the tissues of the fly agaric mushroom (Amanita muscaria), may facilitate the transport of the mushroom's active compounds into the brain, thereby enhancing their overall psychoactive effects. This hypothesis is supported by the observation that the hallucinogenic effect from consuming the whole mushroom is greater than what would be expected from the quantity of active substances it contains, suggesting that mannitol acts as a co-factor that improves brain penetration and potency.
Medical Hypotheses
April 5, 2023
Jianmeng Song, Yasaman Kambari, Aron Amaev et al.
2 citations
No Summary
Medical Hypotheses
October 1, 2020
E S Lansky
1 citation
The eye contains serotonin and its receptors, and drugs that bind to these receptors may affect vision. Selective serotonin reuptake inhibitors (SSRIs) can impair ocular function, while other serotonin-binding drugs might improve it. Harmine, a naturally occurring alkaloid found in plants such as Passiflora, Peganum, and Banisteriopsis, is proposed as a candidate for improving vision. At individualized low doses, these plants are minimally hallucinogenic and well tolerated, with potential long-lasting benefits from one or few administrations. The hypothesized mechanism involves tuning serotonergic receptors in the eye. Blinded research with harmala alkaloid-containing plants, using psychedelic therapy methods, could assess visual acuity in presbyopia.
Medical Hypotheses
March 1, 2021
Baland Jalal
Sleep paralysis is a condition in which a person, while paralyzed, may hallucinate terrifying ghosts—often faceless shadows, but also full figures like cat-like creatures or witches. This paper proposes a neuroscientific account explaining why these hallucinations occur and why they typically appear as faceless shadows. The account focuses on the distinct computational styles of the right and left hemispheres, suggesting that ghost hallucinations and out-of-body experiences during sleep paralysis are primarily mediated by activity in key right-hemisphere regions. The visual system's economizing nature, including surface interpolation and shortcuts, is invoked to explain faceless humanoid-shadows and sensed presence. The hypothalamus and anterior cingulate may also be involved in related dissociative states. The author notes that empirical research is needed to validate this hypothesis.
Medical Hypotheses
October 1, 2021
Nicholas S Patniyot
In schizophrenia, disruptions in self-awareness and a loss of agency point to alterations in consciousness. Applying Ned Block's concept of access consciousness helps clarify deficits in reflective thought and autonoetic thinking. Theories such as Global Workspace Theory describe consciousness as recursive and integrative, functions that access consciousness contributes to. In schizophrenia, an integrative deficit prevents prior cognitive outputs from being incorporated into new working schemas. Disrupted cortical circuits related to integrative functions may cause subsequent cognitive dysfunction and symptoms. Constitutive failures to integrate information could block experiential unity and content management in autonoetic consciousness. Aberrant reasoning in schizophrenia, including problems with hierarchical relational reasoning and source monitoring, may also reflect alterations in access consciousness.
Medical Hypotheses
May 1, 2021
Dipti Magan, Raj Kumar Yadav
The right hemisphere counterpart of Broca's area, typically associated with language in the left hemisphere, may play a role in attention-focused meditation. In twelve healthy, right-handed male long-term meditators, positron emission tomography showed significantly greater activity in the right Broca's area during meditation compared to baseline, while left Broca's area activity increased only slightly. The authors propose that this right-hemisphere region could be important for attention and may have implications for understanding and treating attention deficits and language or speech disorders.
Medical Hypotheses
March 1, 2020
Seyedsaeid Ahmadvand, Bijan Peik, Babak Azarfar
A philosophical and thermodynamic critique of Beshkar's conjecture that qualia and consciousness have a negentropic nature. The author disputes the fundamental assumptions of Beshkar's argument, which posits that qualia are building blocks of consciousness, both are subjective and non-observable, and arise from negentropic processes that nonetheless obey the second law of thermodynamics. The critique examines these assumptions from a thermodynamic perspective and scrutinizes the concept of subjectivity in more detail, arguing against the claim that quantum laws erase traces of negentropic processes. The paper engages with the theoretical foundations of qualia and consciousness without presenting empirical data.