Mismatch Negativity Responses in Children With a Diagnosis of Childhood Apraxia of Speech (CAS)

Purpose: To evaluate whether a hypothesis suggesting that apraxia of speech results from phonological overspecification could be relevant for childhood apraxia of speech (CAS). Method: High-density EEG was recorded from 5 children with CAS and 5 matched controls, ages 5-8 years, with and without CAS, as they listened to randomized sequences of CV syllables in two oddball paradigms: phonemic (/ba/, /pa/) and allophonic (/pa/, /p(h)a/). Results: In the phonemic contrast condition, mismatch negativity (MMN) responses to oddball sounds were observed for the typically developing (comparison) group but not the CAS group, although a component similar to an immature mismatch response was apparent. The allophonic contrast did not elicit MMN responses in the comparison group, but in the CAS group, an MMN-like response was observed. Conclusion: The authors propose that these preliminary findings are consistent with a view of CAS as a disorder that not only affects motor planning but also has a phonological component.