mercoledì 13 aprile 2016

Aborto e coscienza - Ronald Bailey Liberation Biology

So are fetuses capable of having conscious experiences? In support of the Pain-Capable Unborn Child Protection Act, the House Judiciary Committee cited various studies for the assertion that 20-week old fetuses feel pain. One of the more eloquent of the experts who testified on behalf of the bill was Dr. Maureen Condic, an associate professor of neurobiology and adjunct professor of pediatrics at the University of Utah School of Medicine. Condic agrees that the psychological aspects of pain are important but counters that “we can measure certain physical, neurological, and endocrine responses to painful stimuli.” She then outlines the developmental process of a fetal nervous system including the “most primitive response to pain, the spinal reflex,” which is in place by 8 weeks. By 18 weeks, nerve connections between the spinal cord and thalamus in the developing brain are completed. The thalamus is generally considered to be the part of the brain that relays sensory data to the cortex, which is the outer layer of the brain generally associated with higher mental functions such as thought and action. 
Condic does acknowledge that 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.” But she believes that the fetal neural structures needed to detect noxious stimuli are in place by 8 to 10 weeks of development. She further asserts: “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 as a newborn or an adult would have.” As evidence that it is possible to feel pain without a cortex Condic cites the fact that children born without a cortex and animals whose cortices have been removed will withdraw from pinches, burns, and so forth. As further evidence for fetal pain, Condic cites studies showing that various medical treatments applied to fetuses in the womb boost their stress hormone levels.
On the basis of this evidence, Condic contends, “Direct experimental evidence from adult humans contradicts that the assertion...that mature pain perception requires cortical circuitry.” Her conclusion actually rather begs the question of whether perception equals experience.
Most researchers agree with Condic on the developmental course of the fetal brain, but they come to a very different conclusion with regard to fetal pain. In her testimony, Condic criticized three comprehensive analyses of fetal neurological development and its implications for fetal pain—one by the American Congress of Obstetricians and Gynecologists, one by the Journal of the American Medical Association (JAMA), and one by the United Kingdom’s Royal College of Obstetricians and Gynaecologists (RCOG).
Domanda: l'embione sente dolore?
The RCOG's report, Fetal Awareness: A Review of Research and Recommendations for Practice was issued in March 2010. “In reviewing the neuroanatomical and physiological evidence in the fetus,” it found, “it was apparent that connections from the periphery [of the fetal body] to the cortex are not intact before 24 weeks of gestation and, as most neuroscientists believe that the cortex is necessary for pain perception, it can be concluded that the fetus cannot experience pain in any sense prior to this gestation.” In other words, while fetuses can react to pain, at the 24-week stage of brain development there is no subject present that is capable of experiencing pain.
The RCOG report also found that even after 24 weeks of development, fetuses abide “in a continuous sleep-like unconsciousness or sedation” that “can suppress higher cortical activation in the presence of intrusive external stimuli.” Since fetuses cannot experience pain before 24 weeks, the RCOG recommends against administering pain-relieving drugs when treating fetuses in the womb except in cases when it’s necessary to immobilize them.
The 2005 JAMA review came to a similar conclusion: “Evidence regarding the capacity for fetal pain is limited but indicates that fetal perception of pain is unlikely before the third trimester. Little or no evidence addresses the effectiveness of direct fetal anesthetic or analgesic techniques.” The JAMA article focused on the subjective nature of pain, noting that the “psychological nature of pain also distinguishes it from nociception [the detection of noxious stimuli], which involves physical activation of nociceptive pathways without the subjective emotional experience of pain.” In a June 20, 2013, statement, the American Congress of Obstetricians and Gynecologists cited the JAMA review’s conclusion that “fetal perception of pain is unlikely before the third trimester” and added, “Although ultrasound monitoring can show intrauterine fetal movement, no studies since 2005 demonstrate fetal recognition of pain.”