What version of FSL?
Peace,
Matt.
On 5/9/14, 11:21 AM, "SUBSCRIBE FSL Anonymous" <[log in to unmask]>
wrote:
>Hi Matt,
>Thanks for helping me understand this. Resolution is 3x3x4 mm, TR is 1.5
>seconds, and 920 time points. No concatenation. When I did ICA on a
>different, shorter, dataset (3x3x3mm, TR 2s, 196 timepoints), I similarly
>got a 150-300 components with smoothed data and much less with unsmoothed
>data.
>Cheers, Kajsa
>
>On Fri, 9 May 2014 10:56:18 -0500, Matt Glasser <[log in to unmask]> wrote:
>
>>What is your resolution, TR, and number of time points per run? Did you
>>use one long run or concatenate across runs?
>>
>>Smoothing would only decrease gaussian noise, which ICA is trying not to
>>put into components to begin with.
>>
>>Peace,
>>
>>Matt.
>>
>>>Thanks Christian!
>>>
>>>Ok, that makes sense. Somehow I had imagined smoothing would have the
>>>opposite effect by decreasing noise sources...
>>>
>>>On to my next worry: From what I've seen people generally get many fewer
>>>components, also with spatially smoothed data. My dataset is pretty
>>>standard, although the stimuli are very complex (movies). Does anyone
>>>have any ideas about why I get so many more components than other
>>>people?
>>>I'm worried I've made some mistake. Or doesn't this happen sometimes and
>>>it's just that I haven't heard of it in the literature? I'm pretty new
>>>to
>>>this method.
>>>
>>>Many thanks!
>>>Kajsa
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