In <2961288583.0.p00907 at psilink.com>
"Richard E. Cytowic MD" <p00907 at psilink.com> writes:
> There is rather a lot of inter-subject variability not only in
>gross brain anatomy, but in functional mapping (electrical). On the
>face of it, you propose to measure what cannot be measured.
.....
Thank you for your suggestion. I expected a response like yours.
I searched for the papers you mentioned, but they were so old that
our library(it's a large library, though..) didn't have. But I found
another article by Ojemann "Cortical language localization in left, dominant
hemisphere", 1989, Journal of Neurosurgery 71:316-326, which notes
the variability of language localization determined by intraoperative
stimulation. According to that article, their distributions were mosaic-
patterned, varied regardless of gyration.
But actually, intersubject averaging is so widely accepted in PET
activation studies, that without it, no new activated foci can be
detected. As a matter of course, as you imagine, resolution is not
good(as large as 8-10mm). What I actually am about to do is non-linear
transformation. It means that transforming the brain PET image
non-linearlly(or distorting) before averaging so that each corresponding
point is overlapped more precisely. Currently, only linear
transformation is done. We expect by non-linear transformation, the
ability of detection (or signal/noise ratio) is increased compared with
linear transformation, and want the theoretical background.
------
Tetsuji Rai MD trai at twics.co.jp, 74610.1537 at compuserve.com
Department of Radiology, Hospital attached to University of Tokyo
Home: 5-12-21-301, Toyotamakita, Nerimaku, Tokyo 176, Japan
Tel: +81-3-3557-3936
Fax: +81-3-3993-0323
