Figure 4.

Modulation of BOLD Signal across Brain ROIs by Feeding or Either Individual or Combined Gut Hormone Infusions

(A–D) Subjects underwent a 90 min infusion of saline (fasted saline) as a control. They also had four further infusions: saline after a standard breakfast (A), PYY_3-36 after an overnight fast (B), GLP-1_{7-36 amide} after an overnight fast (C), and combined PYY_3-36 + GLP-1_{7-36 amide} after an overnight fast (D). During each infusion, a BOLD fMRI scan was performed, incorporating a picture processing task where images of food and nonfood were shown. The mean percent BOLD signal change when subjects viewed images of food compared with when they viewed images of nonfood is shown for each of the infusions administered as a comparison with the fasted saline infusion: ^∗p = 0.015 for fed saline < fasted saline and p = 0.012 for PYY + GLP-1 < fasted saline. ^∗∗p = 0.005 for PYY < fasted saline. Data are shown for individual ROIs (amygdala, insula, caudate, nucleus accumbens [N Acc], OFC, and putamen), combined for left and right hemispheres and grouped for 15 subjects, shown as mean ± SEM. Abbreviations: PYY, PYY_3-36; GLP-1, GLP-1_{7-36 amide}. See also Figure S2.