Research by Karen Froud and Reem Khamis-Dakwar Accepted by American Journal of Speech Language Pathology (AJSLP)
High density EEG study conducted in the Neurocognition of Language Lab adds new evidence to the view that childhood apraxia of speech is a disorder that affects not only motor planning, but also has a phonological component.
Karen Froud
Teachers College, Columbia University
Reem Khamis-Dakwar
Adelphi University
Purpose: The underlying deficit in Apraxia of Speech is a debated topic, and it remains unclear whether distinctions exist between causal mechanisms involved in developmental versus acquired apraxia. One proposal suggests that apraxia of speech results from phonological over-specification (Dogil, Mayer, & Vollmer, 1996). To evaluate whether this hypothesis could be relevant for Childhood Apraxia of Speech (CAS), we investigated brain responses to auditorily-presented phonemic and allophonic speech sound contrasts, in children with CAS compared to typically-developing (TD) peers.
Method: High-density EEG was recorded from 5 children with CAS and 5 matched controls, aged 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/, /pha/).
Results: In the phonemic contrast condition, mismatch negativity (MMN) responses to oddball sounds were observed for the TD 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.
Conclusions: We propose that these preliminary findings are consistent with a view of CAS as a disorder that affects not only motor planning, but also has a phonological component.
AJSLP Papers in Press
Published online May 7, 2012
American Journal of Speech-Language Pathology 2012; doi:10.1044/1058-0360(2012/11-0003)
http://ajslp.asha.org/cgi/content/abstract/1058-0360_2012_11-0003v1
Published Friday, May. 11, 2012