Neural responses to human voice and hemisphere dominance for lexical-semantic processing--an fMRI study.
OBJECTIVE
In our previous functional magnetic resonance imaging (fMRI) study, we determined that there was distinct left hemispheric dominance for lexical-semantic processing without the influence of human voice perception in right-handed healthy subjects. However, the degree of right-handedness in the right-handed subjects ranged from 52 to 100 according to the Edinburgh Handedness Inventory (EHI) score. In the present study, we aimed to clarify the correlation between the degree of right-handedness and language dominance in the fronto-temporo-parietal cortices by examining cerebral activation for lexical-semantic processing.


METHODS
Twenty-seven normal right-handed healthy subjects were scanned by fMRI while listening to sentences (SEN), reverse sentences (rSEN), and identifiable non-vocal sounds (SND). Fronto-temporo-parietal activation was observed in the left hemisphere under the SEN - rSEN contrast, which included lexical-semantic processing without the influence of human voice perception. Laterality Index was calculated as LI = (L - R)/(L + R) x 100, L: left, R: right.


RESULTS
Laterality Index in the fronto-temporo-parietal cortices did not correlate with the degree of right-handedness in EHI score.


CONCLUSIONS
The present study indicated that the degree of right-handedness from 52 to 100 in EHI score had no effect on the degree of left hemispheric dominance for lexical-semantic processing in right-handed healthy subjects.
Koeda
M
M
Department of Bioinformatics, Medical Research Institute, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan. koedcom@mri.tmd.ac.jp
Takahashi
H
H
Yahata
N
N
Matsuura
M
M
Asai
K
K
Okubo
Y
Y
Tanaka
H
H
D000328:Adult; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000502:physiology*; D003071:Cognition / Q000502:physiology*; D004292:Dominance, Cerebral / Q000502:physiology*; D005260:Female; D006801:Humans; D007802:Language; D008279:Magnetic Resonance Imaging; D008297:Male; D012660:Semantics; D012815:Signal Processing, Computer-Assisted; D011795:Surveys and Questionnaires; D014831:Voice / Q000502:physiology*