H I Simon
Do you need the unnormalized sulc? It would be pretty easy to put something in
to generate it
Bruce
> On Oct 22, 2015, at 3:23 PM, Simon Vandekar <sim...@mail.med.upenn.edu> wrote:
>
> Hi Bruce,
>
> I chose a random subject from the ADNI dataset and computed the mean and
> variance for the left and right hemispheres separately. It looks like the
> mean is close to 0, however the variance is not 1. Do you think it is
> possible that the surfaces are demeaned, but the units are still something
> meaningful (i.e. not unitless)?
>
>
> sulc = read.table('rh.sulc.asc', header=FALSE, col.names=c('v', 'x', 'y',
> 'z', 'sulc'))
>> mean(sulc$sulc)
> [1] -1.236923e-08
>
>> var(sulc$sulc)
> [1] 0.3276958
>
>> quantile(sulc$sulc)
> 0% 25% 50% 75% 100%
> -1.72503 -0.42128 -0.03963 0.40072 1.80980
>
>
> Thanks again,
> Simon
>
>
>
>
>
> Hi Simon
>
> they are originally mm, but I believe we z-score normalize them so that
> the sulc file is 0 mean and unit variance.
>
> cheers
> Bruce
> On Wed, 21 Oct 2015, Simon
> Vandekar wrote:
>
>> Dear Freesurfer experts,
>>
>> I am reading the manuscript "Cortical Surface-Based Analysis II: Inflation,
>> Flattening, and a Surface-Based Coordinate System" by Fischl, Sereno, and
>> Dale (1999) where the estimation of sulcal depth is described on page 199,
>> however from the description I am still unsure of the exact units of sulcal
>> depth.
>> Are the units for sulcal depth in mm or are they in arbitrary units?
>>
>> Thanks in advance,
>> Simon
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