Background: Research to date indicates that a pre-attentive component of the event-related potential (ERP), the mismatch negativity (MMN), may be utilised to investigate the neurological basis of spoken word processing. As it can be elicited in the absence of attention, the MMN is an ideal neurophysiological tool for measuring auditory processing skills in individuals with aphasia.
Aims: The current study investigated the MMN responses of normal and language-disordered participants to tone and speech stimuli, and to correlate the aphasic MMN data with performance on clinical assessments.
Methods: Six adults with aphasia (71.7 years ±3.0) and six healthy age-, gender-, and education-matched controls (72.2 years ±5.4) participated in the study. Stimuli included complex harmonic tones differing in pitch or duration, and consonant-vowel (CV) speech stimuli (non-word /de: / versus real word /deI/ “day”). Participants were administered a language assessment battery (Western Aphasia Battery (WAB), Psycholinguistic Assessment of Language Processing (PALPA) subtests, phoneme labeling task) to measure their auditory comprehension skills.
Results: The aphasic subjects demonstrated reduced amplitude MMN responses to tones deviating in duration, and to speech stimuli (words and non-words) compared with controls.
Conclusions: The MMN may be used as a technique for investigating general and more specific auditory comprehension skills of individuals with aphasia. The combined use of MMN with clinical assessments may result in improved rehabilitative management of aphasic individuals. Building on these results, further research using the MMN technique is currently investigating the ‘language-action model’ of spoken word processing. Current findings of this model and its clinical correlates will also be presented.