The auditory N1m reveals the left-hemispheric representation of vowel identity in humans.
The cortical correlates of the perception of the sustained vowels /a/, /o/ and /u/ were studied by using whole-head magnetoencephalography (MEG). The three vowels which were located on a line in the space spanned by the first (F1) and second (F2) formants and having equal F2-F1 differences evoked equally strong auditory N1m responses at 120 ms after stimulus onset. The left-hemispheric distribution of the source locations, estimated by equivalent current dipoles, reflected the acoustic similarity of the vowels: the growing distance of the vowels in the F2,F1-space was accompanied by a growing distance between the centres of gravity of activation elicited by each vowel. Thus, direct evidence for the orderly left-hemispheric representation of phonemes in human auditory cortex was found.
Mäkelä
Anna Mari
AM
Apperception & Cortical Dynamics, Department of Psychology, Box 9, University of Helsinki, Helsinki, Fin-00014, Finland. annamake@biomag.hus.fi
Alku
Paavo
P
Tiitinen
Hannu
H
D000328:Adult; D001303:Auditory Cortex / Q000502:physiology*; D001931:Brain Mapping; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D015225:Magnetoencephalography; D008297:Male; D010700:Phonetics; D013067:Speech Perception / Q000502:physiology*