Print

Print


Dear FSL experts, 

I am looking at differences in resting state networks using dual regression to see whether connectivity differs across 3 groups as a function of anxiety.  After setting up the design matrix with the mean-centered values of anxiety, I set up the contrasts below.


	                                   normal	SGA	AGA	Anxiety_norm	Anxiety_SGA	Anxiety_AGA
Slope normal > SGA	              0	 0	0	1	-1	0
Slope SGA > Slope norm	      0	 0	0	-1	1	0
Slope normal > slope AGA      0	0	0	1	0	-1
Slope AGA > slope normal      0	0	0	-1	0	1
Slope SGA > Slope AGA	      0	0	0	0	1	-1
Slope AGA > Slope SGA	      0	0	0	0	-1	1


1.  If a region is statistically significant for the first contrast, does it mean that region has increased connectivity for the normal > the SGA group in relation to anxiety, such that, anxiety has different effects on this region between groups? If this interpretation is correct, how do I visualize the direction of this effect in the program (to see whether increases or decreases in anxiety is related to the increased connectivity of this region); Is there a way to plot the anxiety scores and the activity of that region and across groups or would I extract these values then plot in another program? 


2.  To correct for multiple comparisons using false discovery rate, there's a paper (Veer et al., 2010) that inputted the tfce_corrp difference images and then spatially masked with the binary representation of the pooled group main effects images.  This was to decrease susceptibility to type 1 errors.  I am not understanding how the masking here contributes to a more stringent threshold or which masks to select?

If you could please help me, that would be much appreciated.  Thank you.

Alva