Hugo:
Thanks for the response, and I too want this dialogue to proceed in the
spirit of enquiry, so I apologize if I at all seem snarky. I learned
somewhere, that the most likely and simplest answer is usually the
correct answer. Tortured and unusual answers are often not correct. This
debate about the horse and the cart reminds me so much of the global
climate change debate. Even if sea level rises 10 feet in the next 60
years, and the ice sheets all melt away, there will never be final
conclusive evidence that it is human caused. But, there already is a
consensus among the leading experts in the field that global climate
change is being caused by human activity.
 
Likewise, I believe there will never be final conclusive evidence that
neurobiological differences is what starts the literacy acquisition
problems called dyslexia. But I believe there already is a consensus
among leading researchers. There are researchers who disagree, but they
are far outnumbered by the consensus group. You are correct about the
problems defining who is dyslexic, but that to me does not mean you toss
out all dyslexia research. You interpret that research cautiously. Many
of the studies are published in leading peer-reviewed scientific
journals (Nature Neuroscience, etc.). These journals try not to (and
usually succeed) accept for publication terribly flawed research. 
 
I see many different disciplines over many decades leading to similar
conclusions. People with acquired head injuries in the same brain areas
implicated in the neuro-anatomy and brain scan studies, suddenly have
problems similar to many dyslexics. Animals with induced brain injuries
in those same areas have similar sensory processing deficits. Genetic
mutation studies implicate the same areas. Brain scans show
abnormalities in the function of those areas. Cognitive processes known
to be important in reading are tied to those same areas. A simple
conclusion is that something about differences in those areas is likely
causal in problems learning to read. A more complicated explanation is
that there are a lot of faulty scientists, and a lot of amazing
coincidences. It is not any one of those studies that sways my belief.
It is the aggregate body of combined findings that sways my belief.
 
I agree that the post-mortem evidence implicating the planum temporal is
the shakiest. The evidence implicating the thalamus and white matter
differences is more plausible to me.
 
I have never read any research doubting Galaburda, nor have I seen
reference to it. Can you post some references so that I can read them?
Do you have a copy of Learning Disabilities, by Jack Fletcher et al? As
with Beginning to Read, you might be the only other person I have met
who has read that title.
 
I also mostly agree about the abuse of brain scans. But viewed in
conjunction with the behavioral, anatomical, genetic, and cognitive
processing studies, they seem meaningful to me.
 
Thanks for all of your well thought ideas! You keep me thinking!
 
Brant Hayenga
Educational Diagnostician 
Stapleton Elementary/Rio Rancho Middle School
(505) 896-0667 ext. 226 (District Office)
(505) 891-8473 ext. 519 (Stapleton Elementary)
bhayenga at rrps.net
 
 
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://www.nifl.gov/pipermail/learningdisabilities/attachments/20091104/9a84ed40/attachment.html 
-------------- next part --------------
Please note that RRPS email addresses have changed. Please update your 
address books or distribution lists.