Unaffected sensory processing in FMR1 KO mice

Abstract

Sensory sensitivity problems are a common symptom in autism spectrum disorders and fragile X syndrome. Mainly in the auditory modality, disturbed sensory processing has been found in both fragile-X patients as well as the knockout animals of the corresponding genetic model, the Fmr1 knockout mouse. Here we assessed not only auditory but also visual sensory processing in the second generation Fmr1 KO mice (Mientjes et al., 2006) under freely behaving conditions using electroencephalography readouts. No differences between wildtype and knockout animals were found in single auditory and visual evoked potentials in response to pure sine tones and full-field white light flashes. Visual sensory gating was enhanced in the early but not the late components of the evoked potentials, no changes were found in auditory gating. Synchronization to a steady state flickering visual stimulus seemed to be reduced in the higher harmonic responses of 10Hz, but not 20 or 40Hz, stimulation. However, this effect could not be reproduced in an independent cohort of animals. No differences were found in the intertrial phase consistency, nor in power in response to a chirp stimulus in which the frequency steadily increased. This study could not reproduce earlier found increased amplitudes in auditory stimuli, nor could it convincingly show that synchronization deficits found to be present in response to auditory stimuli also existed in the visual modality. Taken together, no robust auditory and visual processing deficits could be found in the Fmr1 knockout mice. When aiming to study sensory processing in the Fmr1 knockout mice, the appropriate paradigms should be carefully selected to improve translatability and predictive validity