We have data from 200 college students using Freesurfer 4.5  Mac 10.6.8.  We looked at both surface area and volume asymmetries.  For surface area for Triangularis, there is a small leftward asymmetry averaged over the whole sample.  113 participants have leftward asymmetry and 85 have rightward asymmetries.  For volume (for Triangularis), there is no significant asymmetry across the whole sample.  101 showed leftward asymmetry while 96 showed rightward asymmetry.  This isn't surprising because parsT asymmetry is unreliable; sometimes you see it and sometimes you don't.

For pars Opercularis, the results are more robust.  For surface area, there is a highly significant leftward asymmetry averaged over the whole sample; 158 participants have leftward asymmetries while 42 have rightward.  For volume, parsO shows a significant leftward asymmetry across the whole sample.  145 leftward, 55 rightward.

If the latest version of Freesurfer is showing predominately rightward asymmetries for pars triangularis, that doesn't seem right, but we wouldn't expect very strong leftward asymmetries either.



Adam Felton and Christine Chiarello



On Mon, Jun 25, 2012 at 5:55 AM, Bruce Fischl <fischl@nmr.mgh.harvard.edu> wrote:
sure. Thanks for pointing out the BA44 issue.  We'll put together a fix in the next couple of weeks
Bruce

On Mon, 25 Jun 2012, Gabor Perlaki wrote:

Dear Bruce,

I've checked the pars triangularis. It was right-lateralized in 79 subjects
and left-lateralized in only 19 subjects.

Thanks, Gabor

2012/6/23 Bruce Fischl <fischl@nmr.mgh.harvard.edu>
     the structures don't need a threshold. Do you know that pars
     triangularis is left lateralized? For the BAs will get you a
     solution

     On Sat, 23 Jun 2012, Gabor Perlaki wrote:

           Dear Bruce,

           We don't used any thresholding by ourselves, we just
           took BA44 volumes out
           of the text-file in the stats directory.
           Should we use thresholded values instead of the
           volumes reported by the text
           files in the stats directory?
           Could we use the volumes reported by the aparc.stats
           and aseg.stats files
           for any statistical analyses, or do we need
           threshold that structures as
           well?


           Thanks,
           Gabor

           2012/6/23 Bruce Fischl <fischl@nmr.mgh.harvard.edu>
                Hi Gabor

                are you thresholding the BA4 label? In 5.2 we
           will distribute
                some tools to automatically threshold the
           labels so that the
                predicted area has the average area of the
           input labels. The
                right BA44 had more spatial spread than the
           left, so you might
                be including a lot of low probability vertices.

                cheers
                Bruce

                On Sat, 23 Jun 2012, Gabor Perlaki wrote:

                      Dear Bruce,

                      In the paper "Left-right asymmetry in
           volume and
                      number of neurons in adult
                      Broca's area." by Katrin Amunts, 10
           subjects (5 men
                      and 5 women) were
                      studied, and the volume of BA44 was
           greater in the
                      left hemisphere than in
                      the right in all ten cases. So, it is
           very strange
                      that the volume of BA44
                      was greater in the right hemisphere in
           all of the 80
                      subjects analyzed by
                      Eniko.

                      Thanks,
                      Gabor




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