Comparing sliding window correlation and instantaneous phase coherence in fMRI dynamic functional connectivity analysis

Sliding window Pearson correlation (SW) is the most commonly used approach for estimating dynamic functional connectivity (dFC). However, instantaneous phase coherence (PC) has gained popularity as it yields frame-by-frame dFC estimates. This work aimed to compare both metrics by analysing the mean lifetime, probability of occurrence and spatial similarity of dFC states with the canonical resting-state networks (RSNs). We found that the state lifetimes increase in SW compared to PC and with window length, worsening the detection of RSNs for smaller datasets. These findings indicate that the temporal blurring induced by SW compromises the ability to detect faster network dynamics.