Abstract phoneme representations in the left temporal cortex: magnetic mismatch negativity study.
We investigated the brain mechanisms enabling one automatically discriminate phoneme category irrespective of the large inter-speaker variability in the acoustic features of the voices. For this purpose, subjects were presented with 450 different speech stimuli, each uttered by a different speaker, belonging to three vowel categories, while a 306-channel magnetoencephalogram (MEG) was obtained to record the magnetic counterpart of the mismatch negativity (MMNm), elicited only when sensory memory traces for repetitive sounds are formed in the auditory cortex. Despite this wide acoustic variation, category changes elicited prominent MMNm responses, which were considerably stronger in the left than in the right hemisphere in the right-handed subjects. These results implicate the presence of long-term memory traces for vowels, which can recognize the vowel-specific invariant code enabling correct vowel percept even in the presence of realistic acoustic variation.
Shestakova
Anna
A
Cognitive Brain Research Unit, Department of Psychology, University of Helsinki, PO Box 13, FIN-00014, Finland. anna.shestakova@cbru.helsinki.fi
Brattico
Elvira
E
Huotilainen
Minna
M
Galunov
Valery
V
Soloviev
Alexei
A
Sams
Mikko
M
Ilmoniemi
Risto J
RJ
Näätänen
Risto
R
D000328:Adult; D001303:Auditory Cortex / Q000033:anatomy & histology / Q000502:physiology*; D001931:Brain Mapping; D003463:Cues; D005072:Evoked Potentials, Auditory; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D007802:Language; D007807:Language Tests; D015225:Magnetoencephalography; D008297:Male; D008568:Memory / Q000502:physiology*; D013067:Speech Perception / Q000502:physiology*; D014705:Verbal Behavior / Q000502:physiology*