Is your data normalized? If so, have you checked to see what it looks
like without normalization?
What about other contrasts? Do they look similar? Have you tried, say, a
contrast of just a +1 over each key press? Then you should at least see
something in motor cortex.
Meera Paleja wrote:
> Attached is a figure for one subject, but this is a fairly consistent pattern across all my subjects for all contrasts.
>
> This was a high-resolution fMRI experiment that used a medial temporal lobe shim. The task involved seeing an image of an object on the floor of a computerized room. This was followed by the recognition phase, where subjects saw an image with two objects, one in the same location as the original and another in a different location and were asked to indicate which is in the same location using a key press.
>
> The image file attached here is a contrast comparing the recognition phase with a baseline letter task, where participants are asked to indicate whether a displayed letter is a vowel or consonant using a key press.
>
> Meera
> ________________________________________
> From: Chris Watson [[log in to unmask]]
> Sent: Tuesday, March 29, 2011 5:03 PM
> To: Meera Paleja
> Cc: [log in to unmask]
> Subject: Re: [SPM] "dalmation" pattern in data
>
> Could you attach a screenshot? And explain the experiment?
>
> Meera Paleja wrote:
>
>> Hi SPM-ers,
>>
>> I am seeing odd activation patterns in my data, specifically "dalmation-like" activation, where one or two voxel "clusters" are activated throughout the brain, with very few clusters larger than that. Does anyone know what might account for this? I haven't smoothed the data as I am interested in very small regions (hippocampal subregions)- could the lack of smoothing be a reason for these strange patterns?
>>
>> Thanks!
>> Meera
>>
>>
>> Meera Paleja, B.Sc. (Hons.), M.A.
>> PhD. Student, Psychological Science
>> Brain Imaging and Memory Lab
>> Department of Psychology
>> Ryerson University
>> Phone: (416) 979-5000 ex. 2192
>>
>> email: [log in to unmask]
>>
>> “Perhaps the most fascinating and mysterious universe of all is the one within us.” -- Carl Sagan
>>
>>
> >
>
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