"Likewise, the release of stress hormones doesn’t necessarily indicate the experience of pain; stress hormones are also elevated, for example, in the bodies of brain-dead patients during organ harvesting. In order for pain to be felt, he maintains, the pain signal must be able to travel from receptors located all over the body, to the spinal cord, up through the brain’s thalamus and finally into the cerebral cortex. The last leap to the cortex is crucial, because this wrinkly top layer of the brain is believed to be the organ of consciousness, the generator of awareness of ourselves and things not ourselves (like a surgeon’s knife). Before nerve fibers extending from the thalamus have penetrated the cortex — connections that are not made until the beginning of the third trimester — there can be no consciousness and therefore no experience of pain. Sunny Anand reacted strongly, even angrily, to the article’s conclusions. Rosen and his colleagues have “stuck their hands into a hornet’s nest,” Anand said at the time. “This is going to inflame a lot of scientists who are very, very concerned and are far more knowledgeable in this area than the authors appear to be. This is not the last word — definitely not.” Anand acknowledges that the cerebral cortex is not fully developed in the fetus until late in gestation. What is up and running, he points out, is a structure called the subplate zone, which some scientists believe may be capable of processing pain signals. A kind of holding station for developing nerve cells, which eventually melds into the mature brain, the subplate zone becomes operational at about 17 weeks. The fetus’s undeveloped state, in other words, may not preclude it from feeling pain. In fact, its immature physiology may well make it more sensitive to pain, not less: the body’s mechanisms for inhibiting pain and making it more bearable do not become active until after birth."