This post is a part of our Bioethics in the News series
By Tom Tomlinson, PhD
Reported in the New York Times and other media outlets, the study by Zvonimir Vrselja and colleagues used a preservative solution and other ingredients to mimic blood flow in the disembodied brains of four pigs (presumed dead), beginning four hours after the pigs had been slaughtered. They discovered that neurons and other brain cells had resumed metabolic activity, and that individual neurons could carry a signal. (For a lay-friendly account, see Reardon 2019.)
This may be a line of research with tremendous potential. At the modest end the range, it could lead to discovering ways to prevent or reduce irreversible brain damage and death, supplementing or improving techniques already in use, such as hypothermia protocols.
But at the other end, it raises the prospect of reanimating parts of the brain that have “died”; or maybe the whole brain itself. Could raising the dead become common-place in another decade—no longer a miracle?
Could the brain dead be raised from the dead?
It might seem the answer to this question is yes. Following the Uniform Laws Commission recommendation, Michigan like all other states allows that death can be declared under two conditions:
An individual who has sustained either of the following is dead:
(a) Irreversible cessation of circulatory and respiratory functions.
(b) Irreversible cessation of all functions of the entire brain, including the brain stem.
If Vrselja and other researchers eventually develop the ability to reanimate a whole brain, and inside a skull rather than a vat, would this make whole brain death always reversible? At least so long as the rest of the body is functional enough to sustain the brain?
It might seem the answer is “yes.” The reanimated brain would have a full complement of neurons, capable of communicating with one another, and presumably then capable of the consciousness found in any healthy human brain. The functions of the brain would have been restored.
Presuming this is possible, such a prospect raises tremendous challenges to the ethical conduct of research leading up to such an achievement, which is a focus of concern for Farahany and colleagues. We might be creating or experimenting on brains (both human and non-human) capable of consciousness, and perhaps of suffering, but with no means of communicating that to the researchers.
But would the achievement really mean that whole brain death would no longer be an acceptable criterion for death?
I think the answer is no. Whole brain death marks the death of the person, not merely the death of the brain. And it’s the death of the person that matters—to that person, and to those around them.
It will in one sense be “my” brain that has been reanimated, and it will be occupying my body. But it will be “my” brain only in the sense of being causally continuous with my brain when I was still in my senses.
It most certainly will no longer be me. Assume that my brain has in fact died, with all or most of its cells and synapses no longer functioning. On what basis could my consciousness, preferences, memories, and many characteristic failings be recovered? Consciousness is most certainly not located in any specific part of the brain, or any particular type of neuron. It is a global, network phenomenon. With the death of my brain, my network has gone down.
The brain that is recovered may have the capacity to build a network of its own. But it won’t be mine.
Yes, they may be able to revive Porky the Pig’s brain one day. But it won’t be the Porky we know.
Tom Tomlinson, PhD, is a Professor in the Center for Ethics and Humanities in the Life Sciences and the Department of Philosophy at Michigan State University.
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- Caplan A. When Pigs Fly. Bioethics.net. April 22, 2019. http://www.bioethics.net/2019/04/when-pigs-fly/
- Farahany NA, Greely HT, Giattino CM. Part-revived pig brains raise slew of ethical quandaries. Nature. 2019 Apr;568(7752):299-302. https://www.nature.com/articles/d41586-019-01168-9
- Fernández-Espejo D. How we identified brain patterns of consciousness. The Conversation, Feb 6, 2019. https://theconversation.com/how-we-identified-brain-patterns-of-consciousness-111275
- Kolata G. ‘Partly Alive’: Scientists Revive Cells in Brains From Dead Pigs. New York Times, April 17, 2019. https://www.nytimes.com/2019/04/17/science/brain-dead-pigs.html
- Kurisu K, Yenari MA. Therapeutic hypothermia for ischemic stroke; pathophysiology and future promise. Neuropharmacology. 2018 May 15;134(Pt B):302-309. https://www.ncbi.nlm.nih.gov/pubmed/28830757
- Michigan Compiled Laws 1033 Determination of death. http://legislature.mi.gov/doc.aspx?mcl-333-1033
- Reardon S. Pig brains kept alive outside body for hours after death. Nature, 17 April 2019, 283-84. https://www.nature.com/articles/d41586-019-01216-4
- Vrselja Z, Daniele SG, Silbereis J, et al. Restoration of brain circulation and cellular functions hours post-mortem. Nature. 2019 Apr;568(7752):336-343. https://www.nature.com/articles/s41586-019-1099-1
- Youngner S, Hyun I. Pig experiment challenges assumptions around brain damage in people. Nature. 2019 Apr;568(7752):302-304. https://www.nature.com/articles/d41586-019-01169-8