Thanks for the advice!

I re-ran this using 3dttest:

3dttest++ -prefix reg_Young_3dttest \
-mask Mask_Young+tlrc \
-covariates Covariates.txt \
-nomeans \
-center NONE \
-setA Subj \
137 /stats.137_PathInt_nt_tcat2+tlrc'[8]' \
143 /stats.143_PathInt_nt_tcat2+tlrc'[8]' \
147 /stats.147_PathInt_nt_tcat2+tlrc'[8]' \
159 /stats.159_PathInt_nt_tcat2+tlrc'[8]' \
...(more subjects)

Subj Perf
137 -1.159
143 -0.682
147 -.047
159 2.655
...(more subjects)

*The Perf values are z-scores.

Sub-brick 8 is the task minus control (block design) t-stat.

I was reading in the other recent message board post "Correlating behavior measures with fmri data" that to get the r-value from the t-score to run:

3dcalc -a reg_Young_3dttest+tlrc[1] \
-expr '(ispositive(a)-isnegative(a))*sqrt(a*a/(a*a+DF))' -prefix corr \

When I look at the initial output (overlay: reg_Young_3dttest: #1 Subj_Perf_Tstat), I am able to see the q value (FDR), but if I look at the output from the 3dcalc (overlay: corr: #0 Subj_Perf_Tstat), the q value is N/A, and there is no longer any significant activity anywhere.

My questions are:
1) With the goal of looking at the correlation between BOLD and performance, is the t-stat: task minus control the correct sub-brick to use? The "Correlating behavior measures with fmri data" also mentioned the need to "standardize" the fMRI data prior to using 3ddtest++, so I wasn't sure if this subbrick was appropriate.
2) If the above procedure was correct, how do I interpret the "disappearance" of significant activity when I convert from t-scores to corr?

Thanks!