The fetal brain and fetal pain
Prof. Maureen L. Condic
Scientific data regarding fetal brain development and pain perception
The earliest “rudiment” of the human nervous system forms by 28 days (four weeks) after sperm-egg fusion. At this stage, the primitive brain is already “patterned”; i.e. cells in different regions are specified to produce structures appropriate to their location in the nervous system as a whole. … In the region of the brain responsible for thinking, memory and other “higher” functions (the neocortex), the earliest neurons are generated during the fourth week after sperm-egg fusion. …
There is strong scientific evidence that communication between neurons of the brain is established in the seventh week. Synapses, which are the molecular structures required for brain cells to communicate with each other, are detected in the cortex at this time. In animals, synapses are functional immediately and this is likely also true of humans. Thus, the earliest function of the neocortex as a network appears to commence in the seventh week.
The neural circuitry responsible for the most primitive response to pain, the spinal reflex, is in place by 8 weeks of development. This is the earliest point at which the fetus experiences pain in any capacity. And a fetus responds just as humans at later stages of development respond; by withdrawing from the painful stimulus. …
The earliest connections between neurons in the subcortico-frontal pathways (regions of the brain involved in motor control and a wide range of psychological phenomena, including pain perception) are detected by 37 days post sperm-egg fusion and are well established by 8-10 weeks. This indicates that the brain is “wiring” itself in the first trimester, well before reaching the fetal stage of life. …
Connections between the spinal cord and the thalamus, the region of the brain that is largely responsible for pain perception in both the fetus and the adult, begin to form around 12 weeks and are completed by 18 weeks.
The long-range connections within the cortex that some believe to be required for consciousness do not arise until much later, around 22-24 weeks. And these connections continue to develop for an exceptionally long time. Indeed, recent studies indicate that the anatomy of the human brain, and therefore the pattern of brain activity underlying all higher functions (reason, memory, emotion, language, etc.), is not fully mature until approximately 25 years after birth.
What brain structures are necessary for a fetus to feel pain?
To experience pain, a noxious stimulus must be detected. The neural structures necessary to detect noxious stimuli are in place by 8-10 weeks of human development.
There is universal agreement that pain is detected by the fetus in the first trimester. The debate concerns how pain is experienced; i.e., whether a fetus has the same pain experience a newborn or an adult would have. While every individual’s experience of pain is personal, a number of scientific observations address what brain structures are necessary for a mental or psychological experience of pain.
First, it is clear that children born without higher brain structures (‘decorticate’ patients) are capable of experiencing pain and also other conscious behaviors … This indicates that the long-range connections that develop in the cortex only after 22 weeks (and are absent in these patients) are not obligatory for a psychological perception of pain. Similarly, experimental animals that have had the cortex removed also show a vigorous response to painful stimuli, again indicating that late-developing cortical pathways are not required for pain perception and response. The observations of human decorticate patients and experimentally decorticated animals noted above are consistent with what is known about the representation of consciousness and emotion in the brain. …
Finally, direct experimental evidence from adult humans contradicts the assertion of ACOG, JAMA and Royal College of Obstetricians and Gynaecologists that mature pain perception requires cortical circuitry. Ablation or stimulation of the cortex in humans does not affect pain perception, whereas ablation of lower centers, including the thalamus, does. These neurological findings indicate that “mature” pain perception is largely localized to the thalamus. The spino-thalamic circuits required for pain perception are established between 12-18 weeks post sperm-egg fusion.
What we observe about fetal pain
[W]hat we directly observe about fetal pain is very clear and unambiguous. Fetuses at 20 weeks post sperm-egg fusion have an increase in stress hormones in response to painful experiences that can be eliminated by appropriate anesthesia. Multiple studies clearly indicate “the human fetus from 18–20 weeks elaborates pituitary-adrenal, sympathoadrenal, and circulatory stress responses to physical insults.” All of these responses reflect a mature, body-wide response to pain.
Fetuses delivered prematurely, as early as 23 weeks, show clear pain-related behaviors. We know less about infants delivered prior to 23 weeks only because so few are available for study. Strikingly, the earlier infants are delivered, the stronger their response to pain. These and many other direct observations of fetal behavior and physiology have resulted in a clear consensus among professional anesthesiologists (highly specialized physicians who are experts in pain management) that the use of medications to relieve pain is warranted in cases of fetal surgery. Many of the advocates of fetal anesthesia make no claims regarding the qualitative nature of fetal pain, but based on both the scientific literature and on their own observations, they clearly conclude that pain exists for these fetuses and that as physicians they are obligated to address fetal pain medically …
Our own experience; Why fetal pain matters
Imposing pain on any pain-capable living creature is cruelty. And ignoring the pain experienced by another human individual for any reason is barbaric. We don’t need to know if a human fetus is self-reflective or even self-aware to afford it the same consideration we currently afford other pain-capable species. We simply have to decide whether we will choose to ignore the pain of the fetus or not.
From the perspective of neuroscience, it is unclear precisely what “psychological” aspects of a mature pain experience are in place at precisely what point in either human prenatal or postnatal development. It is impossible for me to know with certainty whether another adult, a teenager or a fetus experiences pain in precisely the same manner I do. Yet it is entirely uncontested that a fetus experiences pain in some capacity, from as early as 8 weeks of development. Moreover, most modern neuroscientists have concluded that the thalamic circuitry developed by 18 weeks post sperm-egg fusion is primarily responsible for human experience of pain at all stages of life.
Given that fetuses are members of the human species—human beings like us—they deserve the benefit of the doubt regarding their experience of pain and protection from cruelty under the law.
In light of the scientific facts, the observations of medical professionals, our own experience of pain, and our indirect experience of others’ pain, we must conclude that there is indeed a “compelling governmental interest in protecting the lives of unborn children from the stage at which substantial medical evidence indicates that they are capable of feeling pain.” And this unambiguously requires a 20 week fetus to be protected from pain, as proposed under H.R. 1797 [the Pain-Capable Unborn Child Protection Act].
Members of Congress should be contacted and urged to support the federal Pain-Capable Unborn Child Protection Act.
Editor’s note. These excerpts appeared at prolifemn.blogspot.com.
Source: NRLC News
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