Brain Dev. 2006 Apr 26; [Epub ahead of print]
The development of visual- and auditory processing in Rett syndrome: An ERP study
Stauder JE, Smeets EE, van Mil SG, Curfs LG.
Department of Psychology, Section Neurocognition, Maastricht University, Maastricht, The Netherlands
Abstract
Rett syndrome is a neurodevelopmental disorder that occurs almost exclusively in females. It is characterized by a progressive loss of intellectual functioning and motor skills, and the development of stereotypic hand movements, that occur after a period of normal development. Event-related potentials were recorded to a passive auditory- and visual oddball task in 17 females with Rett syndrome aged between 2 and 60 years, and age-matched controls. Overall the participants with Rett syndrome had longer ERP latencies and smaller ERP amplitudes than the Control group suggesting slowed information processing and reduced brain activation. The Rett groups also failed to show typical developmental changes in event-related brain activity and revealed a marked decline in ERP task modulation with increasing age.Lay Summary
In recording electrical brain activity during the performance of various tasks, it is possible to witness events called event-related potentials (ERPs). ERPs are demonstrations of brain activities that occur in preparation for, or in response to, individual events that can be internal or external to the patient. In this study, ERPs were measured in 2- to 60-year-old Rett females, and compared to non-Rett patients, to investigate the development of auditory- and visual processing. The visual stimuli consisted of a green circle on a black background or a red square on a black background, with intermittent 'novel' stimuli consisting of unique and random configurations of small colored blocks on a white background. Similar types of common/unique stimuli patterns were tested for hearing, as well. Overall, there were major differences in ERP found between the Rett patients and non-Rett individuals at all age level. In general, the Rett groups show slower, reduced, and more irregular information processing in both the visual- and auditory stimuli as compared to the non-Rett group. Interestingly, the data suggest that there may be no levelling or improvement in information processing with increasing age in the Rett subjects. It should be noted that the small number of participants did not allow for more profound statistical analyses of the data - more studies like this will be need to be done to better describe this phenomenon. Nonetheless, this paper outlines remarkable particularities of auditory and visual information processing in the development of Rett syndrome, and may guide future research into this condition.