The Role of Early Auditory Discrimination Deficits in Language Disorders

Language impairments can have a devastating effect on the individual’s life. Brain damage such as stroke may cause varying degrees of impaired language. Even milder language problems, such as developmental dyslexia or specific language impairment, can have long-lasting detrimental effects on the individual’s life, affecting both success at school as well as motivation and even self-esteem. In recent years, the mismatch negativity (MMN) has been intensively applied to study the neural basis of language impairments. These studies have shown that the MMN, which reflects the early stages of cortical sound discrimination, is abnormal in a large variety of language impairments. Furthermore, a close relationship between the MMN and some language disorders is suggested by significant correlations between the MMN and language test results. Further support is provided by follow-up studies suggesting that the MMN parameters may predict future language problems in children and by investigations indicating that intervention programs with an ameliorating effect also concurrently change the MMN. However, when interpreting the implications of MMN results it is important to acknowledge that this response specifically reflects early stages of auditory discrimination and should, therefore, be combined with measures probing the further steps of auditory processing for a more complete picture of the underlying deficits of language. The current review addresses how the MMN can be used in determining auditory impairments in language disorders such as aphasia, dyslexia, autism spectrum, and specific language impairment.