Hello all, 

I conducted a fALFF analysis in conn. I utilized all the default settings, including the standard bandpass filter.  Then when I got to the fALFF portion I checked the "normalization" box.

I am interested in fALFF in the striatum, so I extracted mean fALFF values for three striatal ROIs from the BETA Files in the /results/firstlevel/V2V_01 folder.

I am getting negative fALFF values for all subjects for each of these striatal regions. Is that possible? This is not the case for ALFF values.  Am I doing something wrong when conducting the fALFF analysis? 

I would appreciate any guidance!

Thanks,

Emily

Hi Emily,

The "normalization" option converts the fALFF maps to z-scores, separately for each subject and condition, so zero values simply represent "average" fALFF values within the brain, and positive/negative represent higher/lower than average, respectively. The "normalization" option is typically useful when you want to control for potential global differences in fALFF values across the entire brain (which may be influenced, for example, by between-subjects differences in motion within the scanner) and focus instead on relative/local values. 

Hope this helps
Alfonso
 
Originally posted by Emily Belleau: