Dear Pieter,
dear Mahinda,
just to add my belated 2 cents on this: as (almost) always, there are
many roads that lead to Rome. The elegant script Pieter posted will
yield lateralization curves which I also prefer as they will give a much
better idea of how the data behaves over a range of thresholds, instead
of only looking at a snapshot derived from "significant" voxels, however
defined.
May I add that, for comparison purposes, it may still be nice to have a
single value that allows comparing LIs between subjects, which ideally
will be based on such curves. By now, you will not be suprised anymore
to hear that such an approach is indeed available within my LI toolbox
which I am happy to send to anyone interested enough to send me an
e-mail :) I know, I should have a website, I am working on that...
Best,
Marko
Pieter Vandemaele schrieb:
> Dear Mahinda,
>
> I have written a script to calculate lateralization indeces
> (attachment). It's a pre-beta version, it would be nice if someone else
> would like to test it.
> If someone has comments, feel free to contact me. However, changes may
> take some time due to holidays and higher priority tasks.
> Regards
>
> Pieter
>
> Mahinda Yogarajah schreef:
>> Dear List Users,
>> I am trying to create a lateralisation index for fMRI activation in
>> verbal
>> fluency tasks in individual subjects. I am using the VOI button to
>> create a
>> sphere of 5mm radius around a peak activation. I am then using a script
>> that I have found posted on this list to calculate all the beta values
>> for
>> the voxels from which I am calculating a mean. My questions are as
>> follows:
>>
>> 1) Using the voi button I get no option to 'adjust data' - by default it
>> does not adjust - is there a reason I cannot choose the adjust option and
>> perhaps more importantly what does this adjust for exactly ?
>>
>> 2) Using the VOI button I note that it only picks up voxels that are
>> significant at whatever threshold I am using - is this a problem in
>> view of
>> the fact that when I mirror ny VOI to the other side (which shows less
>> activation in the language task), it will contain far fewer voxels in
>> a VOI
>> of the same size. Is there a way around this ?
>>
>> Thank you.
>>
>> Mahinda
>>
>
--
=====================================================================
Marko Wilke (Dr.med./M.D.)
[log in to unmask]
Universitäts-Kinderklinik University Children's Hospital
Abt. III (Neuropädiatrie) Dept. III (Pediatric neurology)
Hoppe-Seyler-Str. 1, D - 72076 Tübingen
Tel.: (+49) 07071 29-83416 Fax: (+49) 07071 29-5473
=====================================================================
|