Re: Inception
Posted: Tue Feb 15, 2011 12:04 pm
"You're waiting for a train"
http://www.docstoc.com/docs/37729333/DN ... epigenesis
p. 46
http://www.docstoc.com/docs/37729333/DN ... epigenesis
p. 46
Turkewitz writes that differences in the rate of development of the right and left hemispheres might, “in relation to the changes in the nature of the fetal acoustic environment, help to shape hemispheric specialization.”
According to this view, during the period when the right hemisphere is more advanced than the left the intrauterine environment is characterized by a disproportionate amount of internally generated noise. Because of its developmentally more advanced state the right hemisphere would come to be specialized for dealing with the prevailing noise. Later in development the…shift in the acoustic environment to one in which maternal speech became more salient would be coincident with the emergence of the left hemisphere as the more advanced of the two. Because noise would still be present in the intrauterine environment the right hemisphere would be engaged in its processing so that it would be less available for processing the newly prominent maternal speech. This type of input could come to be processed by the left hemisphere both by default and because of its emergence as the now more advanced structure. It is important to note that…relative differences between the hemispheres, even if small in absolute terms, could be sufficient to produce important structural and functional differences. (p. 133-134).
Turkewitz realizes that his position is highly speculative, but I find it quite provocative nonetheless. Even more remarkable is his suggestion that lateralization could be further influenced by the posture and limited mobility that characterize normal fetuses in their final 10 weeks in utero. As fetuses become larger, gross changes in position become increasingly difficult. By the end of pregnancy, fetuses are normally suspended in utero head-down, and facing towards their mother’s right side. In this position, their left ear is closest to their mother’s spine and their right ear is closest to their mother’s abdominal wall. This arrangement, according to Turkewitz, “would be likely to result in differential exposure of the two ears to…maternal speech propagated [down the spine] by bone conduction. This position would also result in differential exposure of the two ears to externally generated sound….fetal posture would accentuate asymmetric differences in the nature of the acoustic environment and could contribute to the development of the hemispheric specialization under discussion” (p. 134).









