Proof of Heaven

APPENDIX B

Neuroscientific Hypotheses  I   Considered  to  Explain My  Experience

In reviewing my recollections with several other neurosurgeons and
scientists, I entertained several hypotheses that might explain my
memories. Cutting right to the chase, they all failed to explain the rich,
robust, intricate interactivity of the Gateway and Core experiences (the
“ultra-reality”). These included:

1. A primitive brainstem program to ease terminal pain and suffering
   (“evolutionary argument”—possibly as a remnant of “feigned-death”
   strategies from lower mammals?). This did not explain the robust,
   richly interactive nature of the recollections.


2. The distorted recall of memories from deeper parts of the limbic
   system (for example, the lateral amygdala) that have enough overlying
   brain to be relatively protected from the meningitic inflammation,
   which occurs mainly at the brain’s surface. This did not explain the
   robust, richly interactive nature of the recollections.


3. Endogenous glutamate blockade with excitotoxicity, mimicking the
   hallucinatory anesthetic, ketamine (occasionally used to explain NDEs
   in general). I occasionally saw the effects of ketamine used as an
   anesthetic during the earlier part of my neurosurgical career at
   Harvard Medical School. The hallucinatory state it induced was most
   chaotic and unpleasant, and bore no resemblance whatsoever to my
   experience in coma.


4. N,N-dimethyltryptamine (DMT) “dump” (from the pineal, or
   elsewhere in the brain). DMT, a naturally occurring serotonin agonist
   (specifically at the 5-HT1A, 5-HT2A and 5-HT2C receptors), causes
   vivid hallucinations and a dreamlike state. I am personally familiar
   with drug experiences related to serotonin agonist/antagonists (that is,