Figure 2.

Results of the hierarchical cluster analyses on the averaged correlation matrices per sleep stage. Clusters containing bilateral frontoparietal regions were only observed in wakefulness, whereas sleep stage 1 still contained one cluster involving prefrontal regions and one parietal region. The bilateral thalamus was removed from the subcortical cluster and formed a separate cluster in sleep stage 1; slow-wave sleep was characterized by a high hierarchical clustering. See Figure S1 in Supplementary Material for full dendograms with region names.