Hello,
a common problem with a FFX analysis in SPM5 is the 'out of memory' error when using large Datasets for a subject. In my case I failed to run a 6 subjects FFX analysis with 1160 volumes per subject, 34 slices 3x3mm, nearly whole brain, TR=2s. There seems to be no way around the 'out of memory' problem, despite the fact the workstation I am using has 3 GB of RAM.
So, my question now is:
Is it possible and valid to 'fool' SPM5 by creating a new Dataset that contains every second volume, so the total number of volumes will be reduced to 580. Creating a design matrix with the parameter that TR is 4 seconds now. In my case I could even use every 4'th scan, without violating my block design, so the total number of scans would be 290 per person and the TR would be increased to 8 seconds.
Thank you,
Ferenc
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Ferenc Acs
Lehrstuhl Prof. Dr. M. W. Greenlee
Institut für Psychologie
Universität Regensburg
93040 Regensburg
Tel. +49 (0)941 943 3582
Fax +49 (0)941 943 3233
http://www.psychologie.uni-regensburg.de/Greenlee/team/Acs/acs.html
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