Figure 1
From: On wakefulness fluctuations as a source of BOLD functional connectivity dynamics
Definition of dynamic connectivity states. (A) We obtained correlation matrices for each window by computing the pairwise correlation coefficient between the blood oxygenation level-dependent (BOLD) signal time series for all 116 AAL template regions (example signals from two typical participants are presented in panel B). We applied k-means clustering to matrices from all subjects to divide them into dynamic connectivity states (in this example, arrows indicate time windows belonging to four different clusters, C1, C2, C3 and C4). (C) Assignment of each time window to a sleep stage following sleep scoring of the simultaneously acquired EEG data based on AASM scoring rules32 for two exemplary concatenated subjects. The time axis is presented in scan volumes, 1500 volumes correspond to 52 min of scanning (time of repetition: 2.08 s).
