Fig. 1.

Experimental design for acquisition of simultaneous BOLD and CBF data showing stimulus pattern with a 60 s baseline followed by 4 cycles of 20 s of stimulus/60 s of rest and a final 30 s of rest. Tag and control images are alternated each TR (2.5 s), during which two echoes are acquired (TE₁=2.9 ms and TE₂=24 ms). For each echo, the surround average and surround difference of the tag and control images are calculated as shown in order to produce average and difference time courses for each echo as shown in Supplementary Figure S1.