title: Neural responses to human voice and hemisphere dominance for lexical-semantic processing--an fMRI study.
abstract: 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.
authors.affiliation: 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
authors.forename: M
authors.initials: M
authors.lastname: Koeda
authors.forename: H
authors.initials: H
authors.lastname: Takahashi
authors.forename: N
authors.initials: N
authors.lastname: Yahata
authors.forename: M
authors.initials: M
authors.lastname: Matsuura
authors.forename: K
authors.initials: K
authors.lastname: Asai
authors.forename: Y
authors.initials: Y
authors.lastname: Okubo
authors.forename: H
authors.initials: H
authors.lastname: Tanaka
mesh_terms: 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*