Gamma spectral event power is elevated in Fragile X Syndrome and associated with single trial gamma power during auditory chirp

BackgroundFragile X syndrome (FXS) is a neurodevelopmental disorder resulting from silencing of the FMR1 gene. One of the most common and debilitating symptoms of FXS is sensory hyperarousal, especially in the auditory domain. Although the neural mechanisms of auditory hyperarousal in FXS are not well understood, electroencephalography (EEG) studies demonstrate increases in background gamma power during auditory paradigms, which are associated with more severe behavior and impairments in auditory synchronization. MethodsHigh-frequency neural responses to the auditory chirp stimulus were studied in 36 individuals with FXS and 39 controls. Gamma Non-continuous high power events (spectral events) were quantified and compared from source localized EEG recordings. Correlation testing of spectral event properties was performed to averaged EEG features and clinical measures. ResultsOur results show that gamma event peak power was increased in the temporal source of male subjects with FXS (p<0.001, adj. p=0.008) as well as correlated with background average gamma power, while event number, event duration, and frequency span did not differ between groups. Further, absolute event power was positively correlated with clinical measures of obsessive behavior (R=0.63, adj. p=0.011) and stereotypic behavior (R=0.57, adj. p=0.031). ConclusionsOur results indicate that gamma event peak absolute power likely underlies the increased background single trial gamma power observed during auditory processing in FXS, and that the temporal dynamics of gamma activity do not differ.