Auditory evoked magnetic fields in adults with fragile X syndrome.

Hyper-reactivity and anxiety to sensory stimuli have been described in patients with fragile X syndrome (FXS), and may be related to abnormal processing in afferent sensory pathways. We used magnetoencephalography (MEG) to measure auditory responses to pure tones in 11 adults with FXS and 11 non-FXS subjects. The amplitude for the N100m auditory evoked field component was significantly higher for patients with FXS than for subjects. FXS subjects also had less lateralized N100m anterior-posterior dipole locations. These data may suggest that more neurons are activated by acoustic stimuli in FXS, consistent with subjective experience of increased stimulus intensity. Anomalous cerebral lateralization may suggest an early critical window for effects on neocortical development of the fragile X mental retardation protein (FMRP) produced by the FMR1 gene in individuals with FXS.