Large-scale electrophysiological signatures of Williams syndrome: evidence from oscillatory power and brain fluidity

Evidence suggests that Williams syndrome (WS) may be associated with atypical cortical oscillatory activity and large-scale structural and functional anomalies. However, links between whole-brain electrophysiological measures and cognitive performance in WS remain scarce. This study aimed to characterize classical and novel EEG markers in individuals with WS. We examined spectral power, excitation/inhibition (E/I) balance indexed by the aperiodic exponent, and functional connectivity (i.e., derived brain fluidity, an index of connectivity pattern reconfiguration over time) across canonical frequency bands. Two comparison groups were included: a clinical control group comparable in intelligence quotient (IDD) and a typical development control group comparable in chronological age (TD). Moreover, associations between electrophysiological features and cognitive performance were assessed to clarify the neurophysiological substrates underlying variability in the WS cognitive profile. WS was characterized by distinct electrophysiological alterations in the alpha and beta bands. Alpha and beta power distinguished WS from both control groups, with globally reduced alpha power and reduced parieto-occipital beta power. Additionally, we found reduced individual alpha peak frequency in WS, while no group differences emerged for the aperiodic exponent. Another key finding indicated globally increased fluidity in the alpha band in WS relative to both IDD and TD. Notably, higher fluidity within the WS group was associated with better visuomotor performance, suggesting a compensatory role of fluidity within the WS phenotype. These findings provide a characterization of the electrophysiological profile of WS, revealing selective alterations in rhythmic activity and large-scale network dynamics, while suggesting that network-level measures such as fluidity may offer insights into individual differences in cognitive functioning within the syndrome.