July 2004
7
Language development
Evidence versus opinion
Evidence versus opinion
aspect of pervasive developmental
disorders (or
autism spectrum disorders) is the language disorder. So
much more hope can be held out for the child who learns to speak; the child is then regarded
as "high functioning." But
a pedantic, stilted, parrot-like manner of speaking often remains as a life-long handicap; these are
children who will never become quite the person they would have been.
7. Language development
The well-recognized ability of
normal young
children to learn a second language without a foreign accent provides evidence of the importance of the auditory
system for language
learning. The brainstem auditory pathway is myelinated and
functional by 29 weeks of gestation [72, 73], whereas myelination of the temporal and
frontal lobe language circuits continues during the first decade of life [73]. Thus, learning to speak begins before the temporal and
frontal language
areas of the cortex are complete.
Learning to speak requires
"hearing" the boundaries between words and syllables [74]. The healthy human auditory system is then able to
disassemble rapid
streams of speech into elemental
sound components. The rules of syntax are learned with maturation of the
cortical language
areas, which appear to develop as targets of trophic growth factors produced within nuclei of the brainstem
auditory pathway
[75, 76]. Ischemic damage of brainstem auditory nuclei at
birth would then prevent normal development of the language areas during later
childhood.
8. Evidence versus opinion
The evidence from the research with monkeys has been neglected too
long. Windle, Myers and other
investigators held the opinion that brainstem damage was insignificant and at most
responsible for
