Journal ofMedical Ethics 1998;24:237-242

The problematic symmetry between brainbirth and brain deathD Gareth Jones University of Otago, Dunedin, New Zealand

AbstractThe possible symmetry between the concepts of braindeath and brain birth (life) is explored. Since thesymmetry argument has tended to overlook the mostappropriate definition of brain death, thefundamental concepts of whole brain death andhigher brain death are assessed. In this way, a contextis provided for a discussion of brain birth. Differentwriters have placed brain birth at numerous points:25-40 days, eight weeks, 22-24 weeks, and 32-36weeks gestation. For others, the concept itself is opento question. Apartfrom this, it needs to be askedwhether a unitary concept is an oversimplification.The merits of defining two stages of brain birth, toparallel the two definitions of brain death, arediscussed. An attempt is then made to map thesevarious stages of brain birth and brain death onto adevelopmental continuum. Although the results holdbiological interest, their ethical significance is lessevident. Development and degeneration are notinterchangeable, and definitions of death applyspecifically to those who are dying, not those who aredeveloping. I conclude that while a dual concept ofbrain death has proved helpful, a dual concept ofbrain birth still has problems, and the underlyingconcept of brain birth itself continues to be elusive.(Journal ofMedical Ethics 1998;24:237-242)Keywords: Brain birth (life); brain death; whole braindeath; higher brain death; developmental continuum

IntroductionIn the 30 years since the designation of braindeath as a new criterion for death, attention hasbeen directed towards the central role of the nerv-ous system in a number of areas of ethicaldecision-making. The notion that there exists aneurological end-point to human life has led toefforts at defining a neurological starting-point.This latter quest has led to the concept of brainbirth (or brain life), signifying the converse ofbrain death.'-3 Nevertheless, many scientific andethical queries remained.45The quest for a neurological marker of the first

events of human life owes its impetus to theperceived symmetry between processes at thebeginning and end of life. Burgess and Tawia

write: "If conscious experiences ... are the aspectof our lives we value when we lookforward, consid-erations of symmetry dictate that we first acquire acapacity for what we most value in our lives whenwe first become conscious".5 They view thebeginning of consciousness as the beginning of"cortical life". A concrete expression of this trendhas been provided by Sass, who advocates thelegal protection of "personal life (animate life)from the beginning of brain functioning (brainlife) to its end (brain death)".6

Yet brain birth describes a progressive phenom-enon which is leading somewhere new, whereasbrain death describes the final point of anexistence.' 8 The contrast between these two statesis striking, with brain birth centring around a dis-covery concerning personhood and brain deatharound a definition,7 and with the order of neuralembryogenesis standing against the disorder ofneural death.4 The symmetry argument alsosimplifies brain death criteria by overlooking themost appropriate definition of brain death, eitherloss of function of the whole brain (destruction ofthe cerebral hemispheres plus brain stem, or brainstem alone since this is a precursor of whole braindeath), or irreversible loss of higher brainfunctions (total loss of consciousness and aware-ness, loss of cognitive faculties, representing wide-spread destruction of the cerebral hemispheres).This is a distinction between a vitalistinterpretation, with its emphasis on biologicalintegration, and a personalist interpretation, stem-ming from the significance of sentience orconsciousness for the existence of persons. Thecontrast is between "mere human biological life"and "being alive as a person".'°

Unfortunately, brain death has generally pro-vided an undefined context for discussionsregarding how best to describe events at thebeginning of life. For instance, it is not clear whatdefinition of brain death is being used insymmetry-based arguments. This gap is a farmore serious one than generally realized, and thedebate on brain birth can be taken much furtherby exploring its dimensions alongside those ofbrain death.

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238 The problematic symmetry between brain birth and brain death

Brain death - fundamental conceptsWHOLE BRAIN DEFINITIONThe Harvard criteria for a permanently non-functioning brain pointed to total and irreversibleloss of functioning of the whole brain."' A flat elec-troencephalogram (EEG) was recommended as aconfirmatory test.Whole brain death refers to the irreversible ces-

sation of function of both the brain stem andhigher parts of the brain, including the cerebralhemispheres, although in the United Kingdom itrefers to the brain stem alone, on the assumptionthat loss of brain stem functions is rapidlyfollowed by cessation of function of the higherparts of the brain. In other words, brain stemdeath is seen as synonymous with death of theindividual, since loss of functions associated withthe brain stem results in the individual ceasing tofunction as an independent biological unit.'2From this it follows that death does not occur

until both the brain as a whole and the body as awhole are irreversibly dysfunctional. This is a bio-logical concept, and death is recognized as havingtaken place without any reference to a capacity forself-consciousness or personhood. However, inspite of the brain as a whole being considereddead, isolated functions may continue within thebrain, and cellular activity in localized regions ofthe brain may also remain intact.'' "

Although proponents of a whole brain defini-tion allegedly use the entire brain as their criterionof death, the identification of a higher brain func-tion, such as sentience, tends to emerge as anessential feature. For some, a whole braindefinition is an unstable compromise between thedeaths of persons and organisms.'5 It has to beasked whether individuals with intact integrativefunctions (signifying an intact brain stem), butwithout the marks of personhood (damage to thecerebral hemispheres) are alive in any meaningfulsense. Some writers do not think so, arguing thatthe life that continues after destruction of the cer-ebral hemispheres (neocortex) is no more thanmetabolic activity, equivalent to that of a disem-bodied human organ or cell surviving in vitro.'6

HIGHER BRAIN DEFINITIONA higher brain definition refers to destruction ofthe cerebral hemispheres alone, with retention ofbrain stem function. A move in this direction is amove away from utilizing criteria shared withother animals to a definition focusing on functionscharacteristic only of humans. Interest centres onthe irreversible loss of higher brain functions, suchas the capacity for consciousness, and the capacityfor remembering, judging, reasoning, acting,enjoying and worrying. If these are regarded as

characteristic of human existence and of ourmeaning as human persons, they may be regardedas the sole functions of ultimate importance whendefining brain death."' What counts as a livinghuman being is the presence of the capacity forboth organic and mental functioning, rather thanthe persistence of isolated brain stem reflexes fol-lowing destruction of the cerebral hemispheres.The centrality of the person lies at the heart of thehigher brain definition, and this in turn, focusesattention on our humanness and on those respon-sibilities lying at the core of human community.

COMPLEXITY OF BRAIN DEATH

These definitions of brain death highlight thecomplexity of death, the variety of factors to beconsidered, and the range of neurobiological andphilosophical components to be taken intoaccount. 18For many people, there is a difference between

death of the body and death of the brain (regard-less of the definition employed). However, bodilylife is still life, but is this meaningful life in ahuman sense? It is tempting to conclude that themeaningfulness of an individual's existence isopen to question once irreversible higher braindeath is definitely diagnosed: that individual life isat an end, the irreversibility of the conditioneliminating any potential for future relationships,for self-awareness, or for plans of any description.On the other hand, the opposite perspective issuccinctly expressed by Lamb: "Life without con-scious experience may be meaningless, possiblyfutile, but it does not amount to death".'9These considerations are relevant for those of

brain birth. When can an embryo/fetus be said tobe alive in any meaningful sense? Is it at the firstglimmerings of a nervous system (neural plate/neural tube), at the first signs of the potential forconsciousness/sentience (cerebral hemispheresrecognizable/initial manifestation of localizedEEG activity), or when there is sufficient struc-tural organization for the nervous system to func-tion in a coordinated manner (EEG activity char-acterized by little electrocerebral silence)? Is itpossible to translate perspectives on brain deathdirectly into considerations ofbrain birth? If this isdone, different characteristics will emerge asrelevant.

Brain birthThe concept of brain birth has featured inattempts to elucidate a moral point-of-demarcation, prior to which experimental proce-dures may be undertaken on human embryos butafter which they are forbidden.6 20 Numerous

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writers have attempted to pinpoint what theyregard as the biological substratum for personallife,5 21 23 with attention on development of thecerebral cortex and on identifying the firstmoments of conscious experience. Some have setthis at 25-40 days gestation.24 For others, eightweeks gestation represents the point at which thebrain is capable of consciousness. From this pointonwards, the "biography" of the individual hasbegun25; alternatively, this level of brain activitysignifies the emergence of a person,22 makespossible an holistic level of life,2' leads to affectiverecognisability by other people,26 or denotes thebeginnings of sentience.27 28

Goldenring,2 who originally proposed the"brain-life theory", based his view on evidencethat the subcortical brain comes into being as anorganized unit at five weeks, with cerebralhemispheres differentiating at seven weeks, andEEG activity commencing at eight weeks. Accord-ing to the brain-life theory, a human being is alivewhenever a functioning human brain is present.Thus, the commencement of EEG activity is seenas the starting point for human (personal)existence, since it marks integration of the brain asa whole.3 The attractiveness of this theory stemsfrom an apparent symmetry between the begin-ning and end of human existence, using the con-verse of brain death as a model for thinking aboutthe initiation of coordinated neural activity.

Others have sought a much later beginning.Gertler20 proposed 22-24 weeks gestation, on thebasis that the neocortex begins producing EEGwaves at this time. Underlying this proposal is theview that human cognition is the beginning ofcognitive capability and the point at whichprotection of personhood should begin. In similarfashion, Burgess and Tawia5 defined a functioningbrain as one where there is identifiable activity ofthe kind that normal adult brains (cortices)indulge in. They argue that what is required is acritical minimum level of structural organisation,with functional components present and matureenough to perform. On the basis ofEEG readings,they conclude that a fetus becomes conscious at32-36 weeks gestation.The significance ofEEG activity for this discus-

sion is unmistakable. The earliest very localizedEEG activity appears at ten weeks,29 with moregeneralized activity at 22-23 weeks gestation. Thisactivity, however, is discontinuous, with long peri-ods of electrocerebral silence, a characteristic ofthe immature nervous system.30 31 Prematureinfants with gestational ages less than eightmonths have long periods during which the EEGshows no activity. Gradual changes in EEG char-acteristics occur over the first few years of postna-

tal life, until adult patterns predominate aroundage seven or eight years.9

Also relevant here is the issue of fetal awareness,which has been placed at not earlier than 26 weeksgestation by a 1997 working party of the RoyalCollege of Obstetricians and Gynaecologists.32According to this working party, this is theminimum stage of structural development neces-sary to confer awareness upon the developingfetus, with structural integration of peripheralnerves, spinal cord, brain stem, thalamus, andcerebral cortex.

In view of the above, can any one notion ofbrain birth encapsulate the state of developmentor maturity over a 30-week period? This repre-sents 75 per cent of gestation, from early in theembryonic period to late in the fetal period. Sucha vast time period is too crude to prove convincingembryologically, and is too diffuse to prove helpfulethically.

CRITIQUE OF BRAIN BIRTHApart from this consideration, the brain birthconcept is not universally accepted. For Moussaand Shannon,7 it is neither a defensible nor usefulnotion, since it is a metaphysical concept. Thedependence placed on the physical maturity ofone bodily system implies that metaphysical statuscan be inferred from scientific data - a notion thatMoussa and Shannon strongly reject. For them,personhood is a social and moral construct and,they contend, biological realities neither guaran-tee the presence of, nor constitute the definitionof, a person. According to these authors, afunctioning nervous system is a presuppositiononly of physical activity, with an integrated nervoussystem being required for intellectual activity. Asothers have suggested, scientific criteria have arole in helping direct our moral gaze, demonstrat-ing when a nervous system exists with sufficientmaterial complexity to embody those capacitiesjudged morally pertinent.33 The tenor of thesesentiments points towards a definition of brainbirth modelled on a higher brain definition ofdeath - if such a definition is even contemplated atthe beginning of life.

In terms of scientific criteria, the dominant fea-ture of the developing brain is the laying down ofdifferent systems at different times, and the coor-dination of these systems relatively late indevelopment.4 Some developmental sequencescan only begin once the preceding sequence hasbeen completed, some sequences occur relativelylate in fetal life, while others are not completeduntil after birth. Consequently, if brain birth isplaced early, numerous phases of developmentwill not even have been initiated. Hence, if the

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240 The problematic symmetry between brain birth and brain death

concept is to be used, it would seem preferable toplace it at a time when most developmentalsequences have started,4 once again pointing to adefinition based on a higher brain definition ofbrain death.

Is there more than one definition ofbrainbirth?Apart from any problems with the concept ofbrain birth, a crucial question is whether a unitaryconcept is an oversimplification. If there are twodefinitions of brain death, are there two defini-tions of brain birth?The whole brain definition of death refers to the

loss of major brain regions, including the brainstem. Is there a parallel at the beginning of life?Employing the appearance ofbrain stem function-ing as one's criterion, brain birth would be placedat around 6-8 weeks gestation. I shall refer to thisas brain birth I, which is a vitalist interpretation,with its emphasis on biological integration and itsstress on mere human biological life. In contrast, asecond definition may be determined by thebeginning of consciousness at 24-36 weeks gesta-tion. This is brain birth II, which parallels the per-sonalist overtones of the higher brain definition ofdeath, with a sufficiently well-developed neuralorganization to serve as the substratum fromwhich self-consciousness and personal life subse-quently emerge.Do these two clearly delineated definitions of

brain birth promote an understanding of thesignificance of early developmental events? In adevelopmental sequence, brain birth I always pre-cedes brain birth II, while in a degenerative proc-ess at the end of life a higher brain definition ofdeath (cortical/cerebral death) may or may notprecede whole brain (brain stem) death. Thisvariability is unavoidable, since degenerativeprocesses lack the inbuilt sequence of develop-mental milestones. One of the defining features ofwhole brain death in adults is a lack of conscious-ness and an inability to feel pain. Symmetry withthe brain death concept suggests that brain birth Ishould demarcate the beginning of the periodwhen the fetus begins to develop sensation andfeel pain, but as yet, the answer to this problematicquestion remains unclear. Rudimentary sensa-tion seems to occur long before the stage when thenervous system can keep the fetus alive, but untila greater understanding of this process can beachieved, there exist no specific developmentalmilestones that establish the moment when a fetusbecomes brain-alive in this sense.37 Even brainbirth II is surrounded by ambiguity, althoughneural integration and the potential for conscious-

ness, as depicted by cerebral cortical develop-ment, point to a relatively mature nervous system.The realization that two separate timings of

brain birth are feasible enlarges the horizons of thedebate, but at present fails to solve fundamentalqueries at the neurobiological level. This is evenmore pronounced for ethical questions, since weare left with major uncertainty whether brain birthI and/or brain birth II have moral significance.Levels of uncertainty look set to increase whenserious debate is undertaken on the possiblerepercussions of techniques that stimulate non-embryonic cells into totipotency, provide themwith primitive human nervous systems but fail toallow the development of any additional "human"characteristics. What impact would such scientificwork have on the notion that brain birth signifiesmoral value?

A continuum from life to deathIf brain life is taken as a notional indicator of brainfunction, it is possible to use two pathways to tracebrain life. One pathway represents normal devel-opment, from fertilization, through fetal andembryonic stages, to the child/adult, at whichpoint brain life is at a maximum. The other is apathological one, working in reverse, and tracingvarious pathological states as they depart frombrain life at its maximum, with dementia and thepersistent vegetative state (PVS)/anencephalyrepresenting increasing decrements until death ofthe individual occurs. When the various defini-tions of brain death are superimposed upon thesepathways, possible parallels can be exploredbetween normal development on the one handand pathological deviations from the normal onthe other. In this way, it is possible to compare (ina tentative fashion) the degrees of brain lifeevidenced by those designated as being dead usinga whole brain definition in contrast to a higherbrain definition, as well as by anencephalics andthose in a PVS. Against this background, andusing what is known of brain death, the next stepis to ask when a brain can be said to come intoexistence.Using a higher brain definition, the answer lies

somewhere in the vicinity of 24-36 weeks (brainbirth II). If this is the case, the parallelism postu-lated here raises the question whether theembryo/fetus at all stages prior to about 22 weeksgestation can be meaningfully referred to as"brain dead". This is a possibility if a brain birthconcept based on a higher brain definition of deathis accepted. However, the terminology is confusing,since it is difficult to appreciate how something canbe dead when it has never lived. In addition, thedeveloping nervous system is developing into

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"something", whereas the adult brain that is nownon-functioning previously was "something". Theproblems of lack of symmetry remain. A "pre-conscious" nervous system is fundamentallydifferent from a "post-conscious" nervous system;the potential of the first differs significantly fromthe memories represented by the second.An alternative is to adopt a whole brain defini-

tion of death as the model on which to base adefinition ofbrain birth (brain birth I). Taking thisapproach, brain birth is placed at around 6-8weeks gestation, when the nervous system is still ata relatively early stage of development, and theneuromuscular system is sufficiently developedfor spontaneous fetal movements to occur.32Whilethis is feasible, such early neural developmentdoes not constitute a brain-like organization inbiological terms.Even brain birth I does not signify the first

beginnings of the nervous system. This happenswith the appearance of the neural plate (18 daysgestation), and then more obviously with theslightly later appearance of the neural tube (clos-ing around 27 days). These early stages in nervoussystem development do not generally feature indiscussions of brain birth, although they may beutilized in connection with the significance of theprimitive streak or even with the onset ofconsciousness.

In conclusion, although it is possible to placethe two-week embryo, eight-week embryo, 36-week fetus, term fetus, newborn infant and childon a continuum, it is doubtful whether thebiological interest elicited by this is matched byethical significance. Even if an eight-week embryois considered to display less brain life than, say, anadult in a PVS or an adult with dementia, onecannot conclude from this that an embryo at thisstage of development has more of the characteris-tics of brain death than does either of these adultgroups. Definitions of death apply specifically tothose who are dying, not to those who aredeveloping. Development and degeneration arenot interchangeable. The problems encounteredwith translating brain death into neural systemdevelopment serve to highlight the questionablefoundation on which the entire edifice of the brainlife concept is constructed.

Definitions of death are not purely biological,but are informed by moral judgments. While theirbase is, in part, biological, the character of thedefinitions owes more to ethical, social, andreligious values. This applies also to the beginningof human life: hence my suspicions regarding thevalidity of the brain birth concept. Its biologicalbase is significantly more fragile than that of braindeath, and, as a result, far more is demanded of its

ethical and social underpinnings. Brain death isproving a helpful concept, despite the fact that itsdimensions remain open to debate andinterpretation. Brain birth, even in its dual formdiscussed here, continues to be elusive.

AcknowledgementThanks to Barbara Telfer and Robyn Harris fortheir many contributions to my thinking on thistopic.

D Gareth Jones, BSc, MBBS, DSc, FIBiol is Profes-sor ofAnatomy and Structural Biology, University ofOtago. He has also served as Acting Director of theBioethics Research Centre, University of Otago.

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