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.eduwrote:
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 The information in this e-mail is intended only for the person to whom it is addressed. If you believe this e-mail was sent to you in error and the e-mail contains patient information, please contact the Partners Compliance HelpLine at http://www.partners.org/**complianceline<http://www.partners.org/complianceline>. If the e-mail was sent to you in error but does not contain patient information, please contact the sender and properly dispose of the e-mail.
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