Background: Fragile 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. Methods: High-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. Results: Our 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). Conclusions: Our 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.

The authors have declared no competing interest.

This study was supported by NIMH/NICHD Grant U54 HD082008-01 (Huber/Sweeney) and NIH Grant U54 HD104461-01 (Erickson). The sponsor had no further role in the research plan development, analysis, or reporting of results.

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IRB of Cincinnati Children's Hospital Medical Center gave ethical approval for the work in this study.

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