The processing of speech and non-speech sounds in aphasic patients as reflected by the mismatch negativity (MMN).
This study compared the discrimination of speech and non-speech sounds in left-hemisphere stroke patients with aphasia and healthy controls by recording event-related potentials (ERPs) and behavioural responses. It was found that the mismatch negativity (MMN) amplitude for vowel and duration changes in speech sounds was diminished in the patients. In contrast, there was no significant difference between the groups in the MMN for comparable frequency and duration changes in non-speech sounds. In the behavioural session, the patients were slower than the control subjects in discriminating duration changes of both types of sounds. These results suggest that left-hemisphere lesions have differential effects on the discrimination of speech and acoustic features indicating that they have separate neural substrates.
Cognitive Brain Research Unit, Department of Psychology, University of Helsinki, Finland.
Titta
T
Ilvonen
Teija
T
Kujala
Hesham
H
Kozou
Anita
A
Kiesiläinen
Oili
O
Salonen
Paavo
P
Alku
Risto
R
Näätänen
D000161:Acoustic Stimulation / Q000379:methods; D000328:Adult; D001037:Aphasia / Q000503:physiopathology*; D001931:Brain Mapping; D016022:Case-Control Studies; D004569:Electroencephalography / Q000379:methods; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D010700:Phonetics; D011930:Reaction Time; D013063:Speech Discrimination Tests / Q000379:methods; D013067:Speech Perception / Q000502:physiology*; D020521:Stroke / Q000150:complications; D014056:Tomography, X-Ray / Q000379:methods