Commentary on Jansen's Paper

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.