FIGURE 1.

Summary of the paradigms and related brain regions. This side view of the human brain shows the three Brodmann areas (BA) addressed by the tasks used in this study. (A) The panel shows stimuli at three levels of difficulty in the Contour integration (CI) task. These stimuli are addressing long-range connections in the primary visual cortex (V1; BA 17). The collinear chain of Gabor patches forming a horizontally placed egg-shape is hidden in the background of randomly positioned and oriented noise elements. Relative noise density varied through six difficulty levels. (B) Four-element movement-sequence in the Finger tapping (FT) task addressing long-range connectivity of the primary motor cortex (M1; BA 4). Subjects were instructed to touch four other fingers with the non-dominant thumb in a given order which was index – ring – middle –little finger. Participants had to carry out the sequence repetitively, as fast and as correctly as they could. (C) The Navon global–local (Navon GL) task consisted of hierarchical stimuli of geometric shapes where the lines of a larger, “global” shape are composed of much smaller, “local” figures (cc. 10th the size of the large ones). Participants were instructed to identify the shape, either at the global or the local level, depending on the color of the background, which was yellow or blue, respectively. This task requires the use of a set of executive control components such as switching and updating which have neural correlates in the dorsolateral prefrontal cortex (BA 46. BA9).