The idea of phantom limbs although a little abstract at first does not seem to be odd or inconceivable upon further thought. A person who has had an arm for example which has been amputated has experienced years of neuronal inputs from this limb. These pathways, whether "hard wired" or developed, still exist after the limb has been removed. They obviously do not receive much of the sensory information that they once did, but given the elaborate nature and multiple-channel capacity of the nervous system, the maintained use of these pathways is not all that surprising. I would suspect that phantom limbs and other such perceptive senses are not as detailed as their fully functioning predcessors; however they obviously do exitst and function on some level.
I was particularly interested from the article in the feelings of extreme pain which many people claim to suffer from. The perception of pain in a lost limb is not hard for me to understand, however, the extreme and sometimes constant pain are what really intrigued me. Could this possibly be because (at least for those who have lost the limb for one reason or another) that the last time the neuronal pathway was used, it was under extreme stress (ie amputation or injury)? This theory has a flaw though because the article specifically states that even people who were born without a limb still report both perception of the limb as well as extreme pain there. This suggests that the pathway is at least basically internally generated, but somehow this seems to suggest a system too complicated in its intrinsic design. The number of internally programed pathways seems to be almost beyond comprehension. However, as we have discussed before, perhaps only certain--most likely those most essential to basic existance--pathways are totally hard-wired thus reducing the demand for a huge predetermined system.
Fascinating/appropriate thoughts/issues. I'm not sure, though, that the "hard-wired, essential" vs "soft-wired, more flexible" distinction is a good or reliable one. The brain differs from computers (the source of the metaphor) in that its circuitry is both doing the information processing and storing resulting information, so there is probably no sharp border between "hard" and "soft" (and maybe no sharp border demarcating "essential" from everything else). In any case, it is true, as you note, that phantom perceptions needn't depend on prior experience. What do you think of the class suggestion that the discomfort may reflect a mismatch between corollary discharge and (absent) afferent signals? PG