Yes, trying to run tracts from a CC mask might give me more insight
into what's going on. I'll give it a shot.
Thanks, Matt.
Best,
Cherif
------------------------------------------------------------------------------------------
Cherif P. Sahyoun HST-MEMP
Developmental Neuroimaging of Cognitive Functions
C: 617 688 8048
H: 617 424 6956
[log in to unmask]
"Live as if this were your last day. Learn as if you'll live forever"
Ghandi
-------------------------------------------------------------------------------------------
On Sun, Nov 2, 2008 at 11:56 PM, Matt Glasser <[log in to unmask]> wrote:
> Have you tried replicating the tractography method of Zorei et al in your
> data just to see what you get? You should be able to find any significant
> pathway with 5000 samples, although 25000 may give more precision,
> especially in cases where the 2nd fiber direction comes into play.
>
> I don't think you should expect significant interhemispheric connectivity in
> all human brain regions, given the amount of hemispheric specialization in
> humans (relative to other primates).
>
> Peace,
>
> Matt.
>
> -----Original Message-----
> From: FSL - FMRIB's Software Library [mailto:[log in to unmask]] On Behalf
> Of Cherif Sahyoun
> Sent: Sunday, November 02, 2008 9:36 PM
> To: [log in to unmask]
> Subject: Re: [FSL] interhemispheric tracking
>
> Hi Matt,
>
> Funny, I was just downloading your new cerebral cortex paper!
> I've tried a couple of different pathways, all from white matter 2.5mm
> in from functional maps. One example is from the left to the right
> white matter adjacent to the intraparietal sulcus. With seeds in the
> CC, Zorei et al. found good connectivity to the posterior parietal,
> but maybe I need more samples (I'm using 5000) if intra-hemispheric
> connections are much more likely than inter-hemispheric ones and
> causing me to "run out of samples" before I exhaust possibilities?
> I don't think it's a diffusion lines issue, as I've successfully run
> pathways within hemispheres in the same datasets, and the V1 files
> look fine in fslview.
>
> Thanks,
> Cherif
>
> ----------------------------------------------------------------------------
> --------------
> Cherif P. Sahyoun HST-MEMP
>
> Developmental Neuroimaging of Cognitive Functions
>
> C: 617 688 8048
> H: 617 424 6956
> [log in to unmask]
>
> "Live as if this were your last day. Learn as if you'll live forever"
> Ghandi
> ----------------------------------------------------------------------------
> ---------------
>
>
>
> On Sun, Nov 2, 2008 at 11:15 PM, Matt Glasser <[log in to unmask]> wrote:
>> What regions are you trying to track between? Have you verified that your
>> diffusion lines are properly oriented?
>>
>> Peace,
>>
>> Matt.
>>
>> -----Original Message-----
>> From: FSL - FMRIB's Software Library [mailto:[log in to unmask]] On Behalf
>> Of Cherif Sahyoun
>> Sent: Sunday, November 02, 2008 9:13 PM
>> To: [log in to unmask]
>> Subject: [FSL] interhemispheric tracking
>>
>> Hi,
>>
>> I am finding difficulties running probtrackx with a seed mask in one
>> hemisphere and a waypoint in the other. In most subjects, the pathway does
>> not "find its way" across.
>> I am using a hemispheric mask with a decently sized "window" around the
>> corpus callosum to allow passage of samples.
>>
>> Has anyone experienced similar difficulties? I seem to remember a casual
>> conversation about this being a common shortcoming of any tractography
>> method, but don't know if it was ever rationalized...
>>
>> Thanks in advance,
>> Cherif
>>
>
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