This group used magnetoencephalography (MEG) to study the spatio-temporal dynamics of responses involved in sensory processing in the neocortex, and the identify any early changes that might occur in FA. They looked at tactile (TERs) and auditory (AERs) evoked responses and early neocortical change detection responses indexed by the mismatch negativity (MMN) in sixteen FRDA patients and matched healthy subjects. They looked for correlations between the maximal amplitude of each response, genotype and clinical parameters. They found that evoked responses were detectable in all FRDA patients but one. In patients, TERs were delayed and reduced in amplitude, while AERs were only delayed. Only tactile MMN responses at the contralateral secondary somatosensory cortex were altered in FRDA patients. Maximal amplitudes of TERs, AERs and tactile MMN correlated with genotype, but did not correlate with clinical parameters. The authors conclude that in FRDA, the amplitude of tactile MMN responses are reduced and correlate with the genotype, while auditory MMN responses are not altered.
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