Consciousness after death

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This article is about the neuropsychology of consciousness and death. For beliefs about life after death, see Afterlife.

The question of consciousness after death is a common theme in society and culture in the context of life after death. Scientific research has established that the mind and normal waking consciousness are closely connected with the physiological functioning of the brain, the cessation of which defines brain death. However, many people believe in some form of life after death, which is a feature of many religions.

Neuropsychology[edit]

According to neuropsychology, the mind or psyche, as well as consciousness and personality are products of the functioning brain.[1]

There are multiple lines of evidence that support the hypothesis that the functioning of the brain causes the phenomenon of mind; besides the general correlations between brain activity and mental activity that can be observed and documented through functional imaging, the emprical evidence also comes from the affects that manipulations and damages to the brain have on the mind,[2] which strongly suggest that the brain processes in question are not just mere correlations, but the physical basis or causes of mental phenomena.[3][4][5] The reasoning behind this is based on manipulablity or interventionist theories of causation.[6]

What follows are some examples of the evidence for the scientific perspective above. In the case of Phineas Gage, a 25-year-old man survived destruction of one or both frontal lobes by a projectile iron rod and went on to manifest pronounced changes in personality, suggesting a correlation between brain states and mental states.[7] Similar examples abound; neuroscientist David Eagleman describes the case of another individual who exhibited escalating pedophilic tendencies at two different times, and in each case was found to have tumors growing in a particular part of his brain.[8][9] The amygdala processes reactions to violations concerning personal space, and these reactions are absent in persons in whom the amygdala is damaged bilaterally.[10] Monkey mothers who have amygdala damage show a reduction in maternal behaviors towards their infants, often physically abusing or neglecting them.[11] The acquisition of memory and knowledge has a bio-chemical basis.[1] Visual perception is handled by the occipital lobe, which once damaged often leads to blindness (see cortical visual impairment). Various different mental defects have been documented.[12]

Psychopharmaceuticals can be used to temporarily alter perception, mood, consciousness, cognition, and behavior through manipulation of neurotransmission. The evidence for a causal relationship between brain activity and mental activity is further supported by data from the effects of electrical stimulations on the brain, for example scientist Steven Pinker writes that electrical stimulation during surgery can cause a person to have hallucinations that are indistinguishable from reality, such as a song playing in the room or a childhood birthday party.[13] (In addition, see transcranial magnetic stimulation, optogenetics, lesion, and cortical stimulation mapping).

In addition to all of the above, neuropsychology links mental development in individual organisms with brain development.[14][15][16] In intelligent animals, human and non-human alike, consciousness as we know it begins to appear at neonatal stages,[17] and is lost and recovered sporadically in the course of their lifespan—during deep sleep, syncope and sometimes coma, because of a lack of communication between cerebral neurons. Consciousness depends on the integration and functioning of several interconnected networks in the brain, two that are most important are the cerebral cortex—the gray matter that covers the outer layer of the brain, and the other is a structure located in the brainstem, called the reticular activating system (RAS) which keeps the cortex "activated" and aroused by encouraging increased brain activity which is needed in order for the brain to process information in such a way that can give rise to awareness.[18][19][20] (for more information see neural correlates of consciousness and disorders of consciousness).

Brain Death[edit]

In the process of clinical death, the heart stops working and pumping blood to the brain, thereby cutting the brain's essential supply of oxygen and of other less urgent nutrients. In dogs, measurable brain activity ends within 20 to 40 seconds.[21] And during brain death, all brain function halts permanently. As characteristic of all biological cells, brain cells die once deprived of oxygenated blood, destroying the brain. According to the current mainstream neuroscientific view, the mind fails to survive brain death and ceases to exist.[22][23]

Near-death experiences (NDEs)[edit]

Some people who have undergone cardiopulmonary resuscitation report experiencing such sensations as detachment from the body, feelings of levitation, and the presence of a light, happening after cardiac arrest. These are commonly referred to as near-death experiences or NDEs by those who study such phenomenon.[24]

In 2008, academic neurosurgeon Eben Alexander had an NDE while attached to an electroencephalogram which demonstrated a total lack of neural activity. After resuscitation, he found he was able to identify the face of a deceased biological sister whom he had previously not known existed (he had been raised in an adoptive family). Prior to his NDE, Alexander had been non-religious. Afterwards, he gained a definite belief in the existence of an afterlife, and went on to write a book about his life-altering experience. Alexander states that the elaborate, highly detailed, and even prescient experiences he had while his brain activity was clinically non-existent provide definitive proof that consciousness can exist without the need for a functional brain.[25]

Sam Harris, Oliver Sacks, Steven Novella and Michael Shermer have pointed out that it is not entirely clear that Dr. Alexander had the experience during coma. They argue that the experience could have occurred when he was returning from the coma, while his neocortex was coming back "online" and returning to full function. Further criticisms include contesting the claim that the coma led to complete neural inactivity.[26][27][28][29]

Such near-death experiences have been described in medical journals as hallucinatory, and such prescient information supposedly gained from NDEs as merely coincidental and dubious.[30][31][32] Ketamine, a dissociative hallucinogen, has been shown to replicate compounds of near-death experiences.[33][34][35] Lucid dreaming too induces experiences quite similar to those of NDEs.[36][37] The imagery in NDEs varies within cultures.[38][39][40] Rick Strassman advanced the hypothesis that a massive release of the psychedelic dimethyltryptamine (DMT) from the pineal gland prior to death or near-death was the cause of the near-death experience phenomenon.[41][42][43]

See also[edit]

References[edit]

  1. ^ a b Rosenberger, Peter B. MD; Adams, Heather R. PhD. Big Brain/Smart Brain. 18th October, 2011.
  2. ^ Churchland, Neurophilosophy, Ch. 8
  3. ^ http://www.psych.upenn.edu/~mfarah/pdfs/neurosci-and-the-soul-letter.pdf
  4. ^ http://www.academia.edu/2795738/No_Mental_Life_after_Brain_Death_The_Argument_from_the_Neural_Localization_of_Mental_Functions
  5. ^ http://www.closertotruth.com/series/how-brain-scientists-think-about-consciousness#video-3848
  6. ^ "Causation and Manipulability"
  7. ^ Harlow (1868), pp. 339–342.
  8. ^ "Brain tumour causes uncontrollable paedophilia"
  9. ^ Eagleman, Philosophy Bites Podcast, "David Eagleman on Morality and the Brain"
  10. ^ Kennedy DP, Gläscher J, Tyszka JM, Adolphs R (2009). "Personal space regulation by the human amygdala". Nat Neurosci 12 (10): 1226–1227. doi:10.1038/nn.2381. PMC 2753689. PMID 19718035. 
  11. ^ Bucher, K., Myersn, R., Southwick, C. (1970). "Anterior temporal cortex and maternal behaviour in monkey". Neurology 20 (4): 415. PMID 4998075. 
  12. ^ "Symptoms of Brain Injury"
  13. ^ "The Brain: The Mystery of Consciousness"
  14. ^ "COGNITIVE DEVELOPMENT AND AGING: A LIFE SPAN PERSPECTIVE"
  15. ^ http://www.pbs.org/wgbh/pages/frontline/shows/teenbrain/work/adolescent.html
  16. ^ http://www.economist.com/node/9616794
  17. ^ H., Lagercrantz; JP., Changeux. (2009). "The emergence of human consciousness: from fetal to neonatal life". Pediatric research 65 (3): 255–60. doi:10.1203/PDR.0b013e3181973b0d. PMID 19092726. 
  18. ^ Hannaman, Robert A. (2005). MedStudy Internal Medicine Review Core Curriculum: Neurology 11th Ed. MedStudy. pp. (11–1) to (11–2). ISBN 1-932703-01-2. 
  19. ^ "Persistent vegetative state: A medical minefield". New Scientist: 40–3. July 7, 2007.  See diagram.
  20. ^ http://neurology.about.com/od/NervousSystem/a/What-Is-Consciousness.htm
  21. ^ Lind B et al., B; Snyder, J; Kampschulte, S; Safar, P (1975). "A review of total brain ischaemia models in dogs and original experiments on clamping the aorta". Resuscitation (Elsevier) 4 (1): 19–31. doi:10.1016/0300-9572(75)90061-1. PMID 1188189. 
  22. ^ Piccinini, Gualtiero; Bahar, Sonya. "No Mental Life after Brain Death: The Argument from the Neural Localization of Mental Functions" (2011). University of Missouri - St. Louis.
  23. ^ Bernat JL (8 Apr 2006). "Chronic disorders of consciousness". Lancet 367 (9517): 1181–1192. doi:10.1016/S0140-6736(06)68508-5. PMID 16616561. 
  24. ^ Mobbs, D; Watt, C. (2011). There is nothing paranormal about near-death experiences: how neuroscience can explain seeing bright lights, meeting the dead, or being convinced you are one of them. Trends in Cognitive Sciences. Volume 15, Issue 10. pp. 447-449.
  25. ^ Alexander, Eben. (2012). Proof of Heaven: A Neurosurgeon's Journey into the Afterlife. Simon & Schuster
  26. ^ Harris, Sam (12 October 2012). "This Must Be Heaven". Retrieved 28 July 2013. 
  27. ^ Shermer, Michael (April 2013). "Proof of Hallucination". Retrieved 28 July 2013. 
  28. ^ Sacks, Oliver (12 December 2012). "Seeing God in the Third Millennium". Retrieved 28 July 2013. 
  29. ^ http://theness.com/neurologicablog/index.php/proof-of-heaven/
  30. ^ Buzzi, Giorgio. "Correspondence: Near-Death Experiences." Lancet. Vol. 359, Issue 9323 (June 15, 2002): 2116-2117.
  31. ^ Britton, Willoughby B. and Richard R. Bootzin. "Near-Death Experiences and the Temporal Lobe." Psychological Science. Vol. 15, No. 4 (April 2004): 254-258.
  32. ^ Blackmore, Susan: Dying to Live: Near-Death Experiences (1993). London, Grafton.
  33. ^ Jansen, Karl L. R. (1995) Using ketamine to induce the near-death experience: mechanism of action and therapeutic potential. Yearbook for Ethnomedicine and the Study of Consciousness (Jahrbuch furr Ethnomedizin und Bewubtseinsforschung) Issue 4 pp55–81.
  34. ^ Jansen, Karl L. R. (1997) The Ketamine Model of the Near Death Experience: A central role for the NMDA Receptor. Journal of Near-Death Studies Vol. 16, No.1
  35. ^ Ring, Kenneth. Ketamine - Near Death and Near Birth Experiences Dr Karl Jansen
  36. ^ Green, J. Timothy (1995). "Lucid dreams as one method of replicating components of the near-death experience in a laboratory setting". Journal-of-Near-Death-Studies 14: 49. "A large phenomenological overlap among lucid dreams, out-of-body experiences, and near-death experiences suggests the possibility of developing a methodology of replicating components of the near-death experience using newly developed methods of inducing lucid dreams. Reports on the literature of both spontaneous and induced near-death-experience-like episodes during lucid dreams suggest a possible protocol." 
  37. ^ Lynne Levitan; Stephen LaBerge (1991). "Other Worlds: Out-of-Body Experiences and Lucid Dreams". Nightlight (The Lucidity Institute) 3 (2-3). 
  38. ^ Near-Death and Out-of-Body Experiences in a Melanesian Society by Dorothy E. Counts]
  39. ^ Varieties of NDE
  40. ^ Eleven Thai Near-Death Experiences
  41. ^ Rick Strassman (with Slawek Wojtowicz, Luis Eduardo Luna and Ede Frecska), "Inner Paths to Outer Space: Journeys to Alien Worlds through Psychedelics and Other Spiritual Technologies", 376 pages, Park Street Press, 2008, ISBN 978-1-59477-224-5
  42. ^ Rick Strassman, DMT: The Spirit Molecule: A Doctor's Revolutionary Research into the Biology of Near-Death and Mystical Experiences, 320 pages, Park Street Press, 2001, ISBN 0-89281-927-8
  43. ^ Rick Strassman, Hallucinogens (chapter), in Mind-Altering Drugs: The Science Of Subjective Experience, 402 pages, Oxford University Press, 2005, ISBN 0-19-516531-4