Neural synchronization deficits linked to cortical hyper-excitability and auditory hypersensitivity in fragile X syndrome.

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Neural synchronization deficits linked to cortical hyper-excitability and auditory hypersensitivity in fragile X syndrome.

Mol Autism. 2017;8:22

Authors: Ethridge LE, White SP, Mosconi MW, Wang J, Pedapati EV, Erickson CA, Byerly MJ, Sweeney JA

Abstract
BACKGROUND: Studies in the fmr1 KO mouse demonstrate hyper-excitability and increased high-frequency neuronal activity in sensory cortex. These abnormalities may contribute to prominent and distressing sensory hypersensitivities in patients with fragile X syndrome (FXS). The current study investigated functional properties of auditory cortex using a sensory entrainment task in FXS.
METHODS: EEG recordings were obtained from 17 adolescents and adults with FXS and 17 age- and sex-matched healthy controls. Participants heard an auditory chirp stimulus generated using a 1000-Hz tone that was amplitude modulated by a sinusoid linearly increasing in frequency from 0-100 Hz over 2 s.
RESULTS: Single trial time-frequency analyses revealed decreased gamma band phase-locking to the chirp stimulus in FXS, which was strongly coupled with broadband increases in gamma power. Abnormalities in gamma phase-locking and power were also associated with theta-gamma amplitude-amplitude coupling during the pre-stimulus period and with parent reports of heightened sensory sensitivities and social communication deficits.
CONCLUSIONS: This represents the first demonstration of neural entrainment alterations in FXS patients and suggests that fast-spiking interneurons regulating synchronous high-frequency neural activity have reduced functionality. This reduced ability to synchronize high-frequency neural activity was related to the total power of background gamma band activity. These observations extend findings from fmr1 KO models of FXS, characterize a core pathophysiological aspect of FXS, and may provide a translational biomarker strategy for evaluating promising therapeutics.

PMID: 28596820 [PubMed - indexed for MEDLINE]

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