109 Neural effects of deep brain stimulation on reward and loss anticipation and food viewing in anorexia nervosa: a pilot study Neuroimaging results Monetary incentive delay task - The MID task revealed a main effect of reward anticipation, showing higher activation n the bilateral thalamus, ventral striatum, insula, medial prefrontal cortex and brain stem during the anticipation of reward compared to neutral cues (See figure 3a). The threshold of p<0.01 uncorrected for visualization purposes was used. Similarly, the main effect of loss anticipation also showed activation in the same regions (See figure 3b). a. Main effects reward anticipation b. Main effects loss anticipation Figure 3. Main effects of task illustrated for AN and HC combined at all timepoints, using a threshold of p<0.01 uncorrected for visualization purpose. At baseline (pre-DBS, T-1), no significant differences in reward anticipation were found between AN and HC. However, significant group (AN and HC) by time (pre- and post-DBS) interactions were found in the right precuneus (xyz=16,-44,60; Z=3.99; p-FWE=0.035; cluster size=132), right dorsal putamen (xyz=26,-10,16; Z=4.69; p-FWE=0.025; cluster size=169), right ventral striatum (xyz=8,0,-6; Z=3.64; p-SVC=0.030), and mOFC (xyz =-2,32,-22; Z=3.55; p-SVC=0.043) (See figure 4 and table 2). Follow-up testing revealed that the interaction effects in the precuneus, putamen and VS could be explained by lower activation for AN post-DBS compared to pre-DBS, whereas in HC, there was higher activation (right precuneus (xyz=12,-42,64; Z=3.97; p-FWE=0.058; cluster size=135), right putamen (xyz=26,-10,16; Z=4.08; p-FWE=0.020; cluster size=85) and right VS (xyz=8,0,-6; Z=3.50; p-SVC=0.041). The interaction effect in the mOFC could be explained by higher activation for AN post-DBS compared to pre-DBS, while in HC, activation was lower (xyz =-2,32,-22; Z=3.55; p-SVC=0.043).
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