Austrian Development Service "HorizonT3000", Harare, Zimbabwe.
The root bark of the Iboga shrub (Tabernanthe iboga) is used in Gabon, Africa, to induce a near-death experience for spiritual and psychological purposes. The pharmacology of ibogaine, a psychoactive indole alkaloid extracted from the bark, has been investigated extensively because of its putative qualities to treat addiction. This review of these studies and neuroscientific approaches to the near-death experience compared with field studies of traditional African rituals has generated new insights into the neurological correlates and the psychological effects and after-effects of the near-death experience. Ibogaine stimulates the cerebellar fastigial nucleus in the same manner as ischemia and leads to a medium-term protection of the brain against glutamate-induced neurotoxicity. At the same time, it induces changes in the autonomic nervous and the cardiovascular systems, which aid in the survival of ischemia: iboga intake and ischemia both lead to slowing of electroencephalogram (EEG) activity (dominance of theta and delta waves), a stimulation of the limbic system, and a dominance of a phylogenetically older branch of the vagus nerve, originating in the dorsal motor nucleus, which lowers the metabolic rate of the body. In conclusion, the near-death experience seems to be the result of a dominance of phylogenetically and ontogenetically old neurological structures and brain waves, which are allowed to show their (para)psychological abilities in the absence of cortical dominance. If parts of the neocortex are still active and permit observation and memory performance, the experience can be integrated within the personality. The newly learned peaceful state ofvagal and subcortical dominance can be actively self-induced. Implications of this model for alternative healing are discussed.