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ketamine_and_near_death_experience [2007-06-12 13:34] – nikketamine_and_near_death_experience [2007-06-12 13:35] – nik
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 Endogenous substances have been found in the brain which bind to the PCP receptor, one of which is a peptide called 'alpha-endopsychosin' (Quirion et al., 1984). However, this is a controversial area of research. We do know that ions such as magnesium and zinc can block the channel, and it may be that a flood of ions occurs rather than large molecules such as peptides. Endogenous substances have been found in the brain which bind to the PCP receptor, one of which is a peptide called 'alpha-endopsychosin' (Quirion et al., 1984). However, this is a controversial area of research. We do know that ions such as magnesium and zinc can block the channel, and it may be that a flood of ions occurs rather than large molecules such as peptides.
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- +1. Depersonalisation
- 1. Depersonalisation+
  
 The depersonalisation theory proposes that the NDE is an adaptive mechanism of the personality which alerts one to the threat of death while potentially overwhelming emotion is held at bay, allowing the reality to be integrated without panic (Greyson, 1983; Noyes and Kletti, 1976a,b). While protecting nerve cells from ischaemic damage is largely irrelevant when one is falling from a cliff, the NDE-producing situation which first resulted in this hypothesis, NMDA receptors would certainly be involved in producing the experience of depersonalisation as they play a central role in cognition and perception. The depersonalisation theory proposes that the NDE is an adaptive mechanism of the personality which alerts one to the threat of death while potentially overwhelming emotion is held at bay, allowing the reality to be integrated without panic (Greyson, 1983; Noyes and Kletti, 1976a,b). While protecting nerve cells from ischaemic damage is largely irrelevant when one is falling from a cliff, the NDE-producing situation which first resulted in this hypothesis, NMDA receptors would certainly be involved in producing the experience of depersonalisation as they play a central role in cognition and perception.
  
  
- +1. Regression in the service of the ego
- 1. Regression in the service of the ego+
  
 This theory maintains that confronting death leads to a cutting off the external world. The result is regression to a pre-verbal level which can be experienced as mystical ineffability (Greyson, 1983). Certainly a loss of contact with the external world is one of the most characteristic effects of ketamine.This is probably the result of blockade of NMDA receptors involved in sensory transmission. NMDA receptors play a key role in the transmission of incoming signals from all sensory modalities (Davies and Watkins, 1983; Greenamyre et al., 1984; Headley et al., This theory maintains that confronting death leads to a cutting off the external world. The result is regression to a pre-verbal level which can be experienced as mystical ineffability (Greyson, 1983). Certainly a loss of contact with the external world is one of the most characteristic effects of ketamine.This is probably the result of blockade of NMDA receptors involved in sensory transmission. NMDA receptors play a key role in the transmission of incoming signals from all sensory modalities (Davies and Watkins, 1983; Greenamyre et al., 1984; Headley et al.,
  
- 1. ; Cotman et al., 1987; Cline et al.,1987; Monaghan, Bridges and Cotman, 1988; Kisvardy et al., 1989; Oye et al.,+1. ; Cotman et al., 1987; Cline et al.,1987; Monaghan, Bridges and Cotman, 1988; Kisvardy et al., 1989; Oye et al.,
  
- 2. ).+2. ).
  
  
  
- 1. A state dependent reactivation of birth memories+1. A state dependent reactivation of birth memories
  
 This theory explains the movement through tunnels towards 'the light' as a memory of being born (Grof and Halifax, This theory explains the movement through tunnels towards 'the light' as a memory of being born (Grof and Halifax,
  
- 1. ). The NDE is thus actually a 'near-birth experience' rather than a 'near-death experience'.+1. ). The NDE is thus actually a 'near-birth experience' rather than a 'near-death experience'.
  
 NMDA receptor blockade could certainly be the underlying mechanism for the release of extremely primitive memories not normally available to consciousness. NMDA receptor blockade could certainly be the underlying mechanism for the release of extremely primitive memories not normally available to consciousness.
  
  
- +1. The NDE as a sensory deprivation phenomenon
- 1. The NDE as a sensory deprivation phenomenon+
  
 This hypothesis maintains that memories may normally be suppressed by a mechanism which acts as a gate, admitting primarily external signals when we are fully conscious and concentrating upon an external task (Siegel,1980, 1981). If this input is dramatically reduced , for example when we are dreaming, have been given drugs such as ketamine, or have just had a heart attack, in combination with a high level of central stimulation (e.g. as would result from excessive glutamate release during hypoxia, ischaemia, epilepsy, or arising without external provocation), stored perceptions are released and become 'organised' by the mind into an experience with some symbolic meaning. According to Ron Siegel (1980), the 'white light' may result from CNS stimulation mimicing light on the retina, and a lowering of the phosphene perceptual threshold. Sensory deprivation itself produces a profound alteration in consciousness which is certainly mediated via NMDA receptors (see 'regression in the service of the ego' above (Lilly, 1961,1978). This hypothesis maintains that memories may normally be suppressed by a mechanism which acts as a gate, admitting primarily external signals when we are fully conscious and concentrating upon an external task (Siegel,1980, 1981). If this input is dramatically reduced , for example when we are dreaming, have been given drugs such as ketamine, or have just had a heart attack, in combination with a high level of central stimulation (e.g. as would result from excessive glutamate release during hypoxia, ischaemia, epilepsy, or arising without external provocation), stored perceptions are released and become 'organised' by the mind into an experience with some symbolic meaning. According to Ron Siegel (1980), the 'white light' may result from CNS stimulation mimicing light on the retina, and a lowering of the phosphene perceptual threshold. Sensory deprivation itself produces a profound alteration in consciousness which is certainly mediated via NMDA receptors (see 'regression in the service of the ego' above (Lilly, 1961,1978).
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 Ketamine blocks this channel at the molecular level and, at a higher level, closes the 'gate' to incoming information (Monaghan, Bridges and Cotman, 1989; Morris et al., 1986; Collingridge, 1987; McNaughton? and Morris, Ketamine blocks this channel at the molecular level and, at a higher level, closes the 'gate' to incoming information (Monaghan, Bridges and Cotman, 1989; Morris et al., 1986; Collingridge, 1987; McNaughton? and Morris,
  
- 1. ; Cotman, Monaghan and Ganong, 1988).+1. ; Cotman, Monaghan and Ganong, 1988).
  
  
  • ketamine_and_near_death_experience.txt
  • Last modified: 2015-03-13 11:44
  • by nik