Text S1 - Structurally-Constrained Relationships between Cognitive States in the Human Brain

We first describe the experimental methods and participants of this study. We then describe the construction of task-positive and task-negative networks, and we highlight the specific anatomical regions of the brain involved in the task-related network couplings , , , and . We then show the distributions of resting- (), attention- (), and memory-state () functional correlations between , , and region pairs. By thresholding these distributions of FC, we show the resulting variations , , and in the number density of structural connections linking strongly-correlated region pairs. Together, these distributions of were used to define the state-space mapping of resting, attention, and memory states shown in Figure 2 of the main text. We show the observed separation between cognitive states is robust to the specific choices made in constructing the representative brain network and in thresholding the resulting distributions of FC. When compared across subjects, this state-space mapping revealed significant inter-subject organization in the relative separations between cognitive states, with subjects naturally organizing into primary and secondary groups (Figure 3 of the main text). We show that the observed organization into such groups is not an artifact of our specific analysis techniques, and we confirm that the primary and secondary groups are statistically similar to the groups identified by a clustering algorithm. Lastly, these groups were shown to exhibit significant differences in behavioral task performance (Figure 4 of the main text). We describe the full set of ANOVA results that were used to confirm the statistical significance of these performance differences. (PDF)