Neurophysiological Changes in Dyslexic Brain Registered by Mismatch Negativity: A Review

Dyslexia is a brier to learning literacy in childhood. There is not a general consensus about its etiology while different theories are presented like phonological awareness deficit or poor visual processing. By the help of instruments that detect structural or functional deficit in the human brain, some differences between normal and dyslexic brain are detected. One of the applicable instruments is Evoked Response Potential and Mismatch Negativity (MMN) registers that help us in early detection of dyslexia. MMN is evoked when any differences in auditory stimuli are detected by the brain and registered easily from scalp. In the present review, we tried to take a brief look to the studies which investigated the MMN in dyslexic children and compared this condition between these patients and normal children.
Methods and Materials: The following databases were searched for studies investigating MMN in Dyslexia from 1998 until 2015: ScienceDirect, Scopus, Willey on line library, Ovid, Google Scholar, PubMed, Scopus, Willey on line library, and PubMed. Taking into account inclusion-exclusion criteria, six papers were selected together with other scientific findings that could help us understand the issue better.
No difference was observed in the normal loci of MMN in normal and dyslexic children, but there were significant changes in early and late MMN that were related to working memory and higher level change detection. It seems that dyslexic children have no good-established lateralized MMN register.