Much ink has been spilled in the medical literature by scientists claiming that mature cortical development and connections are necessary for pain perception. According to the fetal pain deniers, children in the womb cannot experience pain until at least 26 (or so) weeks.
How can such an issue be resolved?
The obvious resolution is this: identify human beings who lack a cortex or who lack normal thalamocortical projections, and ascertain whether they can experience pain. "Knock out mice" are an example of the use of this strategy in determining gene function. We study the effects of the absence of a gene in deficient mice to understand the normal function of the gene.
To understand the normal experience of pain as a function of neuroanatomy and neurophysiology, we should similarly study pain reaction in human beings who lack a cortex or who lack normal thalamocortical projections.
Fetuses are one such subset of human beings--the fact is that they react violently to pain at very early stages of gestation, and efforts of 12-week gestation fetuses to withdraw from noxious stimuli are very well documented (Silent Scream). Ultrasounds of fetuses undergoing various stressful procedures show obvious reactions to pain--the fetuses open their mouths as if to scream, they withdraw violently from the stimulus, and sampling of fetal blood shows massive release of stress-related hormones.
But the evidence for pain experience in the absence of normal cortex or normal thalamocortical projections goes far beyond evidence from fetuses.
There are two kinds of birth defects that leave a person without any cortex at all: hydranencephaly and anencephaly. Patients with hydranencephaly completely lack a cerebral cortex and white matter. The usual cause is a massive stroke during prenatal life. They are left only with a diencephalon (thalamus) and a brainstem and cerebellum. Patients with anencephaly also completely lack a cerebral cortex and white matter. The usual cause is a genetic abnormality that precludes normal brain formation. They too are left only with a diencephalon (thalamus) and a brainstem and cerebellum. I've taken care of scores of patients with these handicaps over 30 years. Their survival after birth is limited. Many die after several months, some live into later childhood (my longest survivor is 10 years).
They all feel pain, despite having no cortex at all. When stuck with a needle or in any way given a painful stimulus, they scream, cry, withdraw, and exhibit intense discomfort. Their autonomic response is identical to that of people without handicaps--their heartbeat increases markedly, their breathing becomes fast and shallow, etc.
They feel pain as surely as you and I feel pain. In fact, my impression is that they feel pain more intensely than people without handicaps.
Furthermore, there are tens of millions of people with neurological disabilities that severely impair cortical function or impair thalamocortical connections. These disorders include lissencephaly, microencephaly, polymicrogyria, among others. These patients often have limited life expectancies, but they all experience pain and are all treated medically with full analgesic therapy--pain killers, local and general anesthesia for surgery, etc.
Probably the largest group of people with markedly deficient corticothalamic projections are people with perventricular leukomalacia (PVL), which is one of the most common causes of cerebral palsy. Many people with PVL have massive global loss of cerebral white matter, which is the brain tissue that comprises connections between the thalamus and the cortex.
Yet people with cerebral palsy obviously experience pain. No one but a sadist would subject a child with cerebral palsy to surgery or other painful procedures without anesthesia. To do so would be worse than malpractice. It would be an actual prosecutable crime.
The claim by some pro-abortion doctors and scientists that lack of a mature cortex or thalamocortical projections precludes the experience of pain is a damnable lie.
Pain is experienced at a subcortical (probably thalamic) level. The cortex is necessary for the interpretation of pain, but is not necessary for the experience of pain. The traditional neuroscientific teaching holds true: pain enters awareness at the thalamus, not the cortex. There is massive evidence to support this: the daily experience of tens of millions of neurologically handicapped people, who experience pain in a very real way.
The only reason this long-understood and uncontroversial fact about the neuroscience of pain perception has been tossed down the memory hole is that this scientific fact casts a bad light on our abortion industry. Ideology trumps science, and when science conflicts with pro-abortion ideology, science gets tossed aside.
Fetuses (once they have a thalamus, which is about 7 weeks) feel pain, just as surely as children with hydranencephaly and cerebral palsy feel pain. To kill a fetus by dismemberment in the womb is the moral equivalent of killing a child with cerebral palsy by dismemberment.
Fetuses feel pain, just as people with severe neurological handicaps feel pain. That the scientific and medical profession does not universally acknowledge this simple fact is disgusting and profoundly evil.