'Brain Waves' When???
Have you heard the common claim
that "fetal brain waves" have been measured very early in pregnancy?
Ever wondered how exactly that was done, and if it's true?
Good question, and no, it's
not true. Instead, as with many "pro-life" assertions, it's based on very
old research that has been taken out of context or misreported. It also
depends on an incorrect, misleading definition of "brain waves," which
is a nontechnical term anyway. Here's the real story.
The assertion is made over and over
again that "fetal brain activity" has been observed or "fetal brain waves"
have been measured at 40, 43, or 45 days, or at 6 weeks after fertilization.
You can find the claim in "pro-life" and sometimes even nonmedical pro-choice
literature. Sometimes a reference is cited, but most often not. This false
information has passed into the general understanding about fetal development
and is simply stated as fact. It is however a factoid instead, which is
the name for a statment repeated often enough that people accept it as
truth, though it's not.
One original source for the claim is
Dr. Hannibal Hamlin's "Life or Death by EEG." This is a speech that was
read before the Section on Nervous and Mental Diseases at the 113th Annual
Convention of the American Medical Association in June 1964, and was printed
in the Journal of the American Medical Association, October 12,
1964 (Vol 190, No 2, pages 112-114). Many claims reference it, for example
this one from "Jack Dean" at a Compuserve address, cited by "The
Pro-Life Advocate" on AOL:
At only 40 days after fertilization
electrical waves as measured by the EEG can be recorded from the baby's
brain, indicating brain functioning47, 48.
47. Hamlin, H. (1964),
"Life or Death by EEG," Journal of the American Medical Association, October
12, 113.
As is typical of "pro-life" writings and websites,
however, it's doubtful whether "Jack Dean" or anyone else has actually
read Hamlin's speech, which makes citing it dishonest. Rather, the claim
is coming from "Dr. Jack" Willke's Abortion:
Questions and Answers:
When is the brain functioning?
Brain waves have been recorded at
40 days on the Electroencephalogram (EEG).
H. Hamlin, "Life
or Death by EEG," JAMA, Oct. 12, 1964, p. 120
What does the speech really say? I've looked
it up in an actual 1964 JAMA, and it's amazing that this antiquated
document is still being used in ways that must have Hannibal Hamlin turning
in his grave. For one thing, it's misleading and deceptive for people to
quote it as if it were original research rather than a personal essay or
opinion piece from one physician, and for another, the research Hamlin
cited is ancient and long superseded.
Not surprisingly for 1964, Dr. Hamlin had
nothing to say about abortion. Instead, the speech is a plea that "competent
application and interpretation of the EEG should gain medical approval
for legal pronouncement of human death." This was not medical or legal
practice in 1964, when only the lack of a heartbeat and breathing determined
death.
As part of the speech, which is largely a
consideration of the brain and not the heart in defining human life and
which includes quotes from Pope Pius XII and the poet Pindar, Hamlin said:
The electrophysiologic
rhythm of the brain develops early. Detailed EEG tracings have been taken
directly from the headend of 16 mm (crown-rump) human embryos at 40-odd
days gestation, recovered from termination of pregnancies (Japan) 6
which revealed irregular slow waves, 0.2-2.0 per second at 10-90 mv
with superimposed fine waves of 30-40 per second at 1-5mv.
Recordings from embryos of 45 to 120 days gestation through surface and
depth electrodes have shown reponses to sedative and stimulant drugs, normal
sleep spindles, and the effect of lack of oxygen by paroxysmal high voltage
slow waves and ultimate electrical silence.7 The intra-uterine
fetal brain responds to biochemical changes associated with oxygen deprivation
by abnormal EEG activity similar to that produced in the adult brain.7
Thus at an early prenatal stage of life, the EEG reflects a distinctly
individual pattern that soon becomes truly personalized. This is not so
the ECG in producing its various types of records at all ages, many specimens
of each type being identical and lacking any individual quality.
This is the entire text regarding fetal "brain
activity." Let's look at the footnotes.
6 is Okamoto and Kirikae's "Electroencephalographic
Studies on Brain of Foetus of Children of Premature Birth and New-Born,
Together With Note on Reactions of Foetus Brain Upon Drugs" (Folia Psychiat
Neurol Jap 1951;5:135-146).
These researchers studied fetuses obtained
through hysterotomy abortions (Cesarean sections), a procedure which is
no longer used. They used electrodes on the surface of the fetal cortex
or buried within it to obtain some of the activity mentioned (the technical
details are incorrectly quoted by Hamlin) at 3 months of pregnancy, or
more than 90 days, not at "40-odd days" as Hamlin said.
The first 7 actually also refers
to this article. Contrary to what Okamoto and Kirikae found, however, in
modern EEG studies "normal sleep spindles" are not seen in premature babies
before 32-35 weeks, according to the medical textbook Electroencephalography:
Basic Principles, Clinical Applications, and Related Fields, and no
activity in the cerebral cortex, drug-stimulated or not, has been observed
by anyone else as early as 120 days. This makes it likely that Okamoto
and Kirikae's readings were mostly artifacts (electroencephalographic waves
that arise from a source other than the brain). In partial corroboration,
though, R. Engel (1964, 1975) is said in Electroencephalography
to have obtained high-voltage medium (neither fast nor slow) waves from
a 19-week (133 day) premature newborn as it died from lack of oxygen. In
short, the Japanese research is either largely obsolete and uncorroborated,
or incorrectly quoted by Hamlin, or both.
The second 7 refers to R.L. Bernstine's
1961 book, Fetal Electrocardiography and Electroencephalography.
At this point Hamlin is talking about late-term fetuses, but the things
he says are still questionable. No one was penetrating women's bodies to
install electrodes on fetal scalps in 1961, or doing external fetal monitoring
during labor, and the claim that the readings were done through a woman's
abdominal wall or vagina and "the mother's brain waves subtracted out"
is preposterous, given the susceptibility of an EEG to interference. Bernstine's
work is not mentioned in any neurology or electroencephalography text I've
searched (though Okamoto and Kirikae are). In any case, this reference
isn't relevant to the "40 days" claim.
'Brain Waves' When??? (2)
Another source for the "40 days" claim is John
R. Goldenring's "Development of the Fetal Brain," a letter published in
the New England Journal of Medicine in 1982. "The Pro-Life Advocate"
website quotes it along with Hamlin:
48. Goldenring,
J. (1982), "Development of the Fetal Brain," New England Journal of Medicine,
August 26, 1982, 564.
And so does Abortion: Questions and Answers:
Brain function, as measured
on the Electroencephalogram, "appears to be reliably present in the fetus
at about eight weeks gestation," or six weeks after conception.
J. Goldenring, "Development
of the Fetal Brain," New England Jour. of Med., Aug. 26, 1982, p. 564
It's important to note that, like Hamlin's speech,
letters published in medical journals are not subjected to the rigorous
peer-review process that research is, and Goldenring's letter simply expresses
his personal opinion that abortion might be banned after 8 weeks based
on brain development:
...[P]hysicians have always
determined when a person is alive by measuring for the presence of certain
"vital signs." ...[W]hen it became possible to replace both cardiac and
pulmonary functions with machines, physicians turned to measuring the function
of the only truly unique and irreplaceable organ — the brain. I submit
that from this effort, the following principle has clearly emerged: The
presence of a functioning human brain means that a patient, a person if
you will, is alive. This is the medical definition of human life. We use
it daily.
Historically, physicians have approached
fetuses in the same way as any other patient, seeking vital signs to determine
the patient's status — hence the emphasis on quickening in legal and medical
thinking before this century. If we consider the fetus with the more sophisticated
modern definition in mind, we find that brain function, as measured by
an electroencephalograph, appears to be reliably present in the fetus at
about eight weeks' gestation.6,7,8
6. Hellegers A. Fetal
development. In: Beauchamp, TL, ed. Contemporary issues in bioethics. Encino,
Calif.: Dickenson, 1978:194-9.
7. Bergstrom RM.
Development of EEG and unit electrical activity of the brain during ontogeny.
In: Jilke LJ, Stanislav T, eds. Ontogenesis of the brain. Praha, Czech:
University of Karlova Press, 1968:61-71.
8. Ellingson RJ,
Guenter HR. Ontogenesis of the electroencephalogram. In: Himwich WA, ed.
Developmental neurology. Springfield Ill.: Charles C. Thomas, 1970:441-74.
As with Hamlin's speech, no original research
is being described here, which makes it dishonest and misleading to quote
it as the source of a claim. But what did the sources Goldenring used have
to say?
Andre Hellegers' "Fetal Development" was first
published in Theological Studies, March 1970, and has often been
republished in collections of writings on abortion. Hellegers was a professor
of obstetrics and gynecology at Georgetown University Hospital and first
director of its Kennedy Institute of Ethics who wrote about biomedical
ethics. As with the other scientists and physicians quoted here, he never
used the term "brain waves," but did write that
By the end of seven weeks
tickling of the mouth and nose of the developing embryo with a hair will
cause it to flex its neck, while at the end of eight weeks there will be
readable electrical activity coming from the brain.9 The meaning
of the activity cannot be interpreted.
Hellegers was talking about eight weeks from
fertilization, not "at eight weeks' gestation" or "six weeks after conception"
as Goldenring and Willke incorrectly claim, which makes it 56 days, not
40. But a bigger problem is that Hellegers was writing another personal
essay, not reporting his own research. His source was D. Goldblatt's
"Nervous System and Sensory Organs" in Intrauterine Development,
a 1968 textbook which wasn't original research either.
On the other hand, Bergstrom's "Development
of EEG and unit electrical activity of the brain during ontogeny" is original
research. Only two courses of study on still-living aborted human embryos
and fetuses have ever been done: Okamoto and Kirikae in Japan in the 1940s,
and Bergstrom and Bergstrom in Finland in the 1960s. Like the Japanese
researchres, the Bergstroms obtained live fetuses "immediately after separation
from the maternal circulation" from hysterotomy abortions, which are no
longer done, so for practical and ethical reasons this kind of research
will not be repeated. But the Bergstroms, who also studied rat, guinea
pig, cat, and chicken embryos, did not find anything that substantiates
a claim of "brain function, as measured on an electroencephalograph" at
six weeks of development, as Goldenring claims.
What they did find was published in various
obscure Scandinavian journals or 30-year-old medical books that are hard
to find. It's also very well described in The
Facts of Life: Science and the Abortion Controversy, a book that's
easily available in paperback.
They found "electrical activity" in fetal
brainstem cells from 10 weeks of pregnancy (56 days after fertilization)
on, but that doesn't mean much. An EEG involves measuring varying electrical
potentials across a dipole, or separated positive and negative charges.
Any
living cell has an electrical potential across its membrane, and any living
structure is a dipole, which explains why people have been able to put
electrodes on plants, hook them up to EEG machines, and get "evidence"
that plants have feelings. But this has nothing to do with "brain waves,"
which are a nontechnical term for a particular kind of varying potentials
produced by certain brain structures that don't even exist in an embryo
and associated with consciousness and dreaming as well as the regulation
of bodily functions.
The Bergstroms did not find electrical activity
of a kind that had anything to do with "brain function" until 84 days (12
weeks) of gestation, or 70 days after conception. The activity then recorded
was not in any way similar to what is seen on a normal EEG, which includes
what people call "brain waves." Rather, the Bergstroms stimulated the fetal
brain stem and were able to record random bursts of electrical activity
which looked exactly like the bursts they got from the fetal leg muscles
when they were stimulated.
'Brain Waves' When??? (3)
At 17 weeks of pregnancy (119 days after fertilization)
R.M. Bergstrom also reported finding "primitive wave patterns of irregular
frequency or intermittent complexes from the oral portion of the brain
stem and from the hippocampus" in the midbrain, according to Electroencephalography.
Even the oldest fetuses that were studied, however, had no "brain waves"
or other kind of signal from the cortex up to 150 or so days.
So all that this research showed, and reported,
about the brain development of 56-to-70-day embryos and fetuses is that
they have live nerve cells present in their brainstems. This is not
the same as "brain waves" (Willke), or "electrical waves as measured by
the EEG, indicating brain functioning" ("The Pro-Life Advocate"), or "coordinating
and individuating brain function" (Goldenring).
In fact, of all the personal essays cited,
only Hellegers got it right when he said that "readable electrical actitivity"
is present at 56 days, but even he was wrong in saying that "The meaning
of the activity cannot be interpreted." It can be interpreted: it means
that fetal brain-stem cells are alive, interconnected, and react to stimulation,
just the way fetal leg-muscle cells do.
Why has this subject not been researched since
the 1960s? Apart from the fact that live aborted embryos and fetuses are
no longer available, researchers now know more about the structure and
development of the cortex, the highest part of the brain and the part that
makes us who we are.
When people, including physicians, talk about
"brain waves" and "brain activity" they are referring to organized activity
in the cortex. While no embryo or fetus has ever been found to have "brain
waves," extensive EEG studies have been done on premature babies. A very
good summary of their findings can be found in Pain
and its effects in the human neonate and fetus," a review article (often
cited by "pro-lifers" writing about fetal pain, but not about brain development)
by K.J.S. Anand, a leading researcher on pain in newborns, and P.R. Hickey,
published in NEJM:
Functional maturity of
the cerebral cortex is suggested by fetal and neonatal electroencephalographic
patterns...First, intermittent electroencephalograpic bursts in both cerebral
hemispheres are first seen at 20 weeks gestation; they become sustained
at 22 weeks and bilaterally synchronous at 26 to 27 weeks.
There are reasons, based on the physics of the
EEG, why this has to be so. Remember, an EEG involves measuring varying
electrical potential across a dipole, or separated charges. To get scalp
or surface potentials from the cortex requires three things: neurons, dendrites,
and
axons, with synapses between them. Since these requirements are not present
in the human cortex before 20-24 weeks of gestation, it is not possible
to record "brain waves" prior to 20-24 weeks. Period. End of story. Scientists
do not attempt to find electrocortical activity in embryos and fetuses
because they know more about the physical structure of the developing human
brain than they did in 1963.
The irony is that Dr. Hannibal Hamlin himself
would have been astounded at the use of his article to defend the personhood
of embryos. The point of his speech, which only casually (and incorrectly)
references fetal brain development, is to point out that
The sanctity of life must
not depend upon cardiologic signs alone, with the brain excluded...Certainly
the human spirit that emerges in man's unique individuality is the product
of his brain, not his heart.
Willke, in Abortion: Questions and Answers,
seems to agree:
Since all authorities accept
that the end of an individual's life is measured by the ending of his brain
function (as measured by brain waves on the EEG), would it not be logical
for them to at least agree that individual's life began with the onset
of that same human brain function as measured by brain waves recorded on
that same instrument?
And Goldenring's discussion of "brain birth"
as opposed to "brain death" makes the same suggestion:
I suggest that as
physicians we should view human existence as a continuum from the first
cell division of the fertilized ovum until the death of the last cell in
the organism. When the coordinating and individuating function of a living
brain is demonstrably present, the full human organism exists. Before full
brain differentiation, only cells, organs, and organ systems exist, which
may potentially be integrated into a full human organism if the brain develops.
After brain death what is left of the organism is once again only a collection
of organs, all available to us for use in transplantation, since the full
human being no longer exists.
But the human part of the brain—the cortex—is
not fully developed, as shown by "brain waves" on an EEG, until very late
in gestation; in fact the EEG continues to change and mature into childhood.
Indeed, the "individuating" function of a person's brain doesn't start
to come into existence until the outer surface of the cortex begins to
develop those deep furrows, grooves, and convolutions (sulci and gyri)
that make a human brain look like a walnut, unlike the smooth brains of
other animals. The furrows and grooves are what enable our brains to have
millions more cells and connections between them than other animals, and
so create our humanity. And the precise configuration of the grooves and
convolutions are part of what determines our individuality; why, for instance,
indentical twins have different personalities, and even, perhaps, why
Einstein was a genius. However, these structures don't begin to form
until the last 2 months of pregnancy.
So I have no objection to saying that
"a human life" or "human personhood" begins when brain waves are measured
on an EEG. That is well into the second half of pregnancy, however, no
matter how many times the "40 days" factoid is repeated.
|
Written
by Margaret
Sykes
Former Guide at About Com