Fig. 1.

a Local maxima with the bilateral superior parietal lobule and middle frontal gyri induced by the main effect of task (2-back >0-back contrast) after the administration of green extract or the of the control substance (FWE cluster level corrected at p < 0.05). b Model space tested in this study. 1 right SPL, 2 left SPL, 3 right MFG, and 4 left MFG. In particular, we contrasted models in which the 2-back WM condition was allowed to modulate, within both hemispheres: (F1) the parieto-frontal connections, (F2) the fronto-parietal connections, or (F3) both. These three intrahemispheric options were crossed with four possibilities which interhemispheric connections might be modulated by the 2-back WM condition, i.e., (a) none (first column of Fig. 1b), (b) the interhemispheric connections between parietal areas (second column of Fig. 1b), (c) the interhemispheric connections between frontal areas (third column of Fig. 1b), or (d) both (fourth column of Fig. 1b). As a result, our model space consisted of 12 alternative models, each of which was fitted to the data from each individual subject