The term Information-theoretic death relates to a definition of death articulated by computer scientist Ralph Merkle that is concerned with the question of when, in the process of death, the "information" (as the term is considered in information theory) stored in the brain can no longer be retrieved; the definition arises in the context of asking at what point during the dying process someone can no longer be preserved with cyronics such that they could be revived again as themselves.[1]
An unreviewed paper Molecular Repair of the Brain by Merkle defined "information-theoretic death":[2]
A person is dead according to the information-theoretic criterion if their memories, personality, hopes, dreams, etc. have been destroyed in the information-theoretic sense. That is, if the structures in the brain that encode memory and personality have been so disrupted that it is no longer possible in principle to restore them to an appropriate functional state, then the person is dead. If the structures that encode memory and personality are sufficiently intact that inference of the memory and personality are feasible in principle, and therefore restoration to an appropriate functional state is likewise feasible in principle, then the person is not dead.
Merkle further suggested, in another unreviewed paper, that at room temperature information-theoretic death occurs gradually after many hours of clinical death as the brain undergoes autolysis.[1][3]
Because of the brain's high metabolism rate, low energy stores, and dependence of aerobic metabolism of glucose, it is exquisitely sensitive to loss of oxygen at normal temperatures; within minutes of the onset of ischemia, ATP levels fall, leading to the failure of ATP-dependent ion transporters and collapse of membrane potential differentials, which causes neurons to initiate programmed cell death.[4]: 559–560 Additionally, as neurons go into crisis, they fall into a feedback loop of glutaminergic excitotoxicity, overwhelming and disrupting synapses,[4]: 563–565 among which information is stored in the brain.[5]: 861–871
References
- ^ a b Merkle, R (1992). "The technical feasibility of cryonics". Medical Hypotheses. 39 (1). Elsevier: 6–16. doi:10.1016/0306-9877(92)90133-W. PMID 1435395.
- ^ Merkle, Ralph (January–April 1994), "Molecular Repair of the Brain", Cryonics, retrieved 2014-12-27 – via Alcor library online
- ^ Wowk, B (2014). "The future of death". Journal of Critical Care. 29 (6). Elsevier: 1111–1113. doi:10.1016/j.jcrc.2014.08.006. PMID 25194588.
- ^ a b Dugan LL, Kim-Han JS. Hypoxic-Ischemic Brain Injury and Oxidative Stress. Chapter 32 in Basic Neurochemistry: Molecular, Cellular and Medical Aspects. Eds. Brady S, et al. Academic Press, 2005. ISBN 9780080472072
- ^ Tsien JZ. Learning and Memory. Chapter 53 in Basic Neurochemistry: Molecular, Cellular and Medical Aspects. Eds. Brady S, et al. Academic Press, 2005. ISBN 9780080472072