J. Moore (
Fri, 26 May 95 13:00:00 -0500

An> Am I mistaken, or do all these journal articles deal with measurements
An> of _physical_ differences in the brain? Until experiments can show true
An> cognitive performance differences directly related to these physical
An> differences, I agree with Mary Beth that we should withhold judgment.
An> Furthermore, there may well be subtle biochemical differences, as well
An> as gross physical differences, which influence cognitive processes--
An> biochemical differences which may or may not be gender related,
An> depending upon stage of reproductive development of the organism.

An> An interesting field of study!

An> Ann

As I mentioned in a previous post, one thing that is commonly *not* done
with these studies is to attempt to determine whether the physical
difference seen is the cause or the result (or some combination) of a
purported difference in the cognitive working of the brain. As I also
mentioned, the only thing I have seen that attempted this study showed
that the difference seen (in the corpus callosum) was apparently
developed rather than innate. This was in one of those short reports
(in *Discover*) about the study and didn't give the source of the
original study, so I haven't tried tracking it down. (For anyone who
has better access to an appropriate library than I, here's the info
from *Discover*; and if anyone does track down the original, I'd like to
know where it is):

Gotttfried Schlaug, Helmut Steinmetz, et al.
University of Dusseldorf

Report in Discover, March 1994, pg. 15 "Music of the Hemispheres"

They did MRI of brains 27 classically trained right-handed male
piano or string players and 27 right-handed male non-muscians.

Quotes from Discover story:

"They found that in the muscians the planum temporale -- a brain
structure associated with auditory processing -- was bigger in the left
hemisphere and smaller in the right than in the non-musicians. The
musicians also had a thicker nerve-fiber tract between the hemispheres.
The differences were especially striking among musicians who had started
training before the age of seven."

"Early musical training, says Schlaug, seems to shape the young brain,
stregthening neural connections and perhaps establishing new ones. The
effect of training was most apparent in the corpus callosum, the
four-inch-long bundle of nerve fibers that connects analogous structures
in the hemispheres."

"Schlaug found that among musicians who had started their training
before the age of seven, the corpus callosum was 10 to 15 percent
thicker than in nonmuscicians or even in late-blooming musicians."

Jim Moore (

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