I would be happy if one of you could help me with the following (rather basic) issue:
I would like to extract the transcallosal connection between the left and right M1. Therefore we created a whole-brain tractogram (10mio streamlines, using ACT) from which I tried to extract the tract of interest. For this I used 3 ROIs as inclusion areas in the tckedit command: One ROI was a Corpus Callosum mask, the two other ROIs were build around the peak activation in fMRI to localize M1 for each individual. These ROIs were build the following way: Created a sphere around the peak activation coordinate big enough to intrude the White Matter and then multiplied it with the White Matter mask to restrict it to the White Matter.
Basically this resulted in the desired tracts, but (even though I know it is not a good idea to count streamlines here) I am a bit in doubt if my results are reliable, because:
- There are some people with very few streamlines (between only 19 - 80)
- There is quite a large variability: Minimum number of streamlines = 19, Maximum = 1.700
My question is: Is this a common result or did I make a mistake or chose the wrong approach?
I would appreciate if one of you could help me!
Best regards, Andrea