ABSTRACT:The authors present a neurobiological model for near-death experiences (NDEs) in an attempt to correlate the biological and psychological domains. This model is based on temporal lobe dysfunction, hypoxialischemia, stress, and neuropeptide/neurotransmitter imbalance. They describe and dis cuss the fundamental contribution of the language system in the construction of verbal reports of NDEs. This model could be seen as a complement to other explanatory domains.The phenomenology of near-death experiences (NDEs) has been de scribed by several authors (Greyson, 1981(Greyson, , 1983a(Greyson, , 1983b(Greyson, , 1985

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A QSAR study was carried out seeking a relationship between the receptor binding affinities and the molecular‐electronic structures of a group of 7‐substituted tryptamines. The results suggest that these molecules interact with the rat stomach fundus serotonergic receptor by charge transfer from the aromatic nucleus and that there are pockets in the receptor which place limits on the sizes of acceptable N‐ and α‐carbon substituents. Also, the charge density available at carbon atom 7 and the size of the C‐7 substituent as estimated by a calculated steric factor seem to make important contributions to an optimal interaction between the IAA and the receptor molecules.

We have analyzed the dependence of the serotonin receptor binding affinity on the electronic and steric reactivity indexes for a group of 5-substituted tryptamines. The approaches employed are a new nonempirical Quantitative Structure-Activity relationship approach and multiple regression analyses. The results suggest that the variation of the receptor binding affinity in 5-substituted tryptamines is related to the variation of the net charge of two atoms and to the steric bulk of the N-substituent. A receptor model is proposed.

We are pleased and grateful for the interest that our work has elicited in the preceding commentaries, and in the following pages we present pertinent responses.Our neurobiological "model" for near-death experiences (NDEs) was intended to be a preliminary work to be completed or modified by others, and may be considered a scientific hypothesis rather than a model. It fulfills the following criteria for scientific hypotheses: it is formally structured and not semantically empty, it is rooted in pre vious scientific knowledge, and it can be empirically tested by scien tific procedures (Bunge, 1979). This last condition deserves commentary. From the strict scientific point of view, NDEs could be provoked in some individuals in order to measure the different biochemical and electrical brain changes corre lated with them. However, accepted and sound ethical principles do not permit that. With the current use of noninvasive brain imaging sys tems, that impediment could be surmounted by the constant monitor This work has received financial support from FONDECYT (Project 1111-88).