Thank you for your help, Daniel.
I have a question to the results I am getting after used my multimask based on the folowing commands:

$ 3dcalc -a ba4_right+tlrc -b ba6_right+tlrc -c ba7_right+tlrc -d ba8_right+tlrc -e ba9_right+tlrc -f ba10_right+tlrc -g ba17_right+tlrc -h ba18_right+tlrc -i ba19_right+tlrc -j ba24_right+tlrc -k ba32_right+tlrc -l ba37_right+tlrc -m ba40_right+tlrc -n ba45_right+tlrc -o ba46_right+tlrc -p ba46_right+tlrc -q ba47_right+tlrc -r amy_right+tlrc -s acc_right+tlrc -t pcc_right+tlrc -u hippo_right+tlrc -v parah_right+tlrc -expr 'step(a)+2*step(b)+3*step(c)+4*step(d)+5*step(e)+6*step(f)+7*step(g)+8*step(h)+9*step(i)+10*step(j)+11*step(k)+12*step(l)+13*step(m)+14*step(n)+15*step(o)+16*step(p)+17*step(q)+18*step(r)+19*step(s)+20*step(t)+21*step(u)+22*step(v)' -prefix RightMultiRegion_mask_MD
$ 3dfractionize -template GroupMCI_mask_group+tlrc -input RightMultiRegion_mask_MD+tlrc -prefix RightMultiRegion_mask_MD_fr -vote -clip 0.2+tlrc
$ 3dROIstats -nzvoxles -sigma -mask RightMultiRegion_mask_MD_fr+tlrc GroupMCI_mask_group+tlrc > BOLD_Group.txt

The columns in the results do not identify which brain region the numbers were collected from. Am I correct in guessing they are in order of the listing of the brain region when I made the multi-mask?
The other question I have is that I am still not sure what the -expr 'step(a) through +22*step(v)' does. I tried reading up on this in the 3dcalc help file and still didn't understand the math behind it. I am using this command based on what my predecessor did with this data set.

Thank you very much!!!
Sabrina