Tästä oli pitkä artikkeli-kommentointi -ketju Journal of Near-Death Studies julkaisussa vuonna 1997. Liitän tiivistelmät niistä tuohon ja pistän loppuun linkin pdf tiedostoon, johon ne kaikki on sidottu.
The Ketamine Model of the Near-Death Experience: A Central Role for the N-Methyl-D-Aspartate Receptor
Journal Journal of Near-Death Studies
Volume 16, Number 1 / March, 1997
Pages 5-26Karl L. R. Jansen1
(1) The Maudsley Hospital, London, United Kingdom
Near-death experiences (NDEs) can be reproduced by ketamine via blockade of receptors in the brain for the neurotransmitter glutamate, the N-methyl-D-aspartate (NMDA) receptors. Conditions that precipitate NDEs, such as hypoxia, ischemia, hypoglycemia, and temporal lobe epilepsy, have been shown to release a flood of glutamate, overactivating NMDA receptors and resulting in neurotoxicity. Ketamine prevents this neurotoxicity. There are substances in the brain that bind to the same receptor site as ketamine. Conditions that trigger a glutamate flood may also trigger a flood of neuroprotective agents that bind to NMDA receptors to protect cells, leading to an altered state of consciousness like that produced by ketamine.
Endogenous Ketamine-Like Compounds and the NDE: If So, So What?
Rick J. Strassman1
(1) Victoria, British Columbia.
This commentary on Karl Jansen's ketamine model for the near-death experience expands upon and raises additional questions about several issues and hypotheses: self-experimentation as a source of data; ketamine's similarities to and differences from classical hallucinogens; the need for quantification of unusual subjective states; clinical research and toxicological implications of this model; drugs as gateways to ldquoreligiousrdquo states; and ldquoevolutionaryrdquo versus ldquoreligiousrdquo significance of naturally occurring compounds released in the near-death state. I suggest future research that could help explicate several of these areas.
Formerly Associate Professor of Psychiatry at the University of New Mexico School of Medicine
Is the Near-Death Experience Only N-Methyl-D-Aspartate Blocking?
Peter Fenwick1
(1) Bethlem Royal and Maudsley Hospitals and Senior Lecturer, Institute of Psychiatry in, London, England
Karl Jansen's interesting hypothesis that near-death experiences (NDEs) result from blockade of the N-methyl-D-aspartate receptor has several weaknesses. Some NDEs occur to individuals who are neither near death nor experiencing any event likely to upset cerebral physiology as Jansen proposed; thus his hypothesis applies only to a subset of NDEs that occur in catastrophic circumstances. For that subset, the clarity of NDEs and the clear memory for the experience afterward are inconsistent with compromised cerebral function. Jansen's analogy between NDEs and ketamine-induced hallucinations is weakened by the fact that most ketamine users do not believe the events they perceived really happened. Temporal lobe seizures do not resemble NDEs as Jansen postulated; they are confusional, rarely ecstatic, and never clear, as are NDEs, nor are they remembered afterward. Jansen's hypothesis assumes the standard scientific view that brain processes are entirely responsible for subjective experience; however, NDEs suggest that that concept of the mind may be too limited, and that in fact personal experience may continue beyond death of the brain.
Which Comes First: Consciousness or Aspartate Receptors?
Igor Kungurtsev1
(1) California Institute of Integral Studies, San Francisco, CA
This paper is a critique of Karl Jansen's hypothesis that near-death and ketamine experiences are caused by blockade of N-methyl-D-aspartate receptors. An assumption that consciousness and its alterations are merely the product of neuronal activity is only one of many possible beliefs about reality. An alternative, which can be verified through one's own direct experience, is that consciousness is always a subject and body is only its object. The objects come and go; consciousness remains.
Commentary on Jansen's Paper
Melvin L. Morse1
(1) Associate Professor of Pediatrics at the, University of Washington, USA
Karl Jansen raises a fundamental and exciting question: Is humankind's consciousness the result of neuronal function, or are there extra-cerebral aspects as well? While his neurotransmitter model of near-death experiences (NDEs) is well described, I find his supporting evidence weak. Methodological differences between studies of ketamine hallucinations and near-death experiences (NDEs) raise doubts about how similar those experiences are phenomenologically. While Jansen's model has electrifying implications, the data required to support his conclusions do not yet exist.
Discussion of “The Ketamine Model of the Near-Death Experience: A Central Role for the N-Methyl-D-Aspartate Receptor,” by Earl L. R. Jansen
Stuart W. Twemlow1, 2 and Glen O. Gabbard1
(1) Topeka Institute for Psychoanalysis, Topeka, KS
(2) University of Kansas School of Medicine, Wichita, KS
We review strengths and weaknesses of Karl Jansen's approach to the near-death experience (NDE). Strengths include his limited goals and avoidance of the trap of explaining all features of the NDE with his theory, although he surprisingly misunderstood our previously published position. Additionally, we applaud the possible intersection of psychological and biological theories, demonstrated in Jansen's biochemical explanations for the individualized variations in manifestation and adaptive role of the NDE. However, he failed to take into account the pitfalls in the use of analogy, modeling oversimplification, and in taking association as causality and causes as meaningful, in the arguments for his theory.
Comments on “The Ketamine Model of the Near-Death Experience: A Central Role for the N-Methyl-D-Aspartate Receptor”
Antonio Bianchi1
(1) General Hospital of Bergamo, Italy
Although ketamine can induce a state similar to a near-death experience (NDE), there is a striking difference between experiences induced by ketamine used in a recreational context and in an operating room. Ketamine is a noncompetitive antagonist of the N-methyl-D-aspartate receptor, as is ibogaine, the main alkaloid of a shrub used in Central Africa to induce NDEs in a religious context. Ibogaine can also elicit different experiences when used in a hallucinatory context or in initiatic rituals, where a superficial state of coma is induced. These data raise the question of whether the chemically-induced NDE-like experience is related to the use of a particular kind of substance or to a genuine comatose state.
Response to Commentaries on "The Ketamine Model of the Near-Death Experience ..."
Karl L. R. Jansen1
(1) The Maudsley Hospital, London, United Kingdom
The commentators on my paper raised several interesting issues. Set and setting do influence drug effects, but they also influence near-death experiences (NDEs). Some NDEs are very anxiety-generating, just like some ketamine experiences, though frightening NDEs have been ignored by most researchers. High frequency, compulsive ketamine use is rare. While dimethyltryptamine (DMT) may induce NDEs, this is far from typical, while NDE-like effects are typical of ketamine. Rapidity of onset is not related to the capacity of a drug to induce NDEs. The reality of endopsychosins is doubtful, but the reality of N-methyl-D-aspartate (NMDA) blocking mechanisms is not. NDEs and dream sleep may involve similar mechanisms. Altered states of consciousness do not require a normally functioning brain. Finally, I discuss the possible evolutionary advantage of the NDE mechanism.
Pistin tuohon pdfän loppuun vielä Strassmanin arvostelun Jansenin kirjasta.
Book Review: Ketamine: Dreams and Realities, by Karl L. R. Jansen. Sarasota, FL: Multidisciplinary Association for Psychedelic Studies, 2001, 355 pp., $14.95 pb. (Available from http://www.maps.org)
Journal of Near-Death StudiesVolume 21, Number 4 / June, 2003
Rick J. Strassman1 Contact Information
(1) University of New Mexico School of Medicine, USA
Kaikki yllä olevat niputettuna yhteeen pdfään:
http://www.filesend.net/download.php?f= ... 096b3fe8c9