Functional MRI study of semantic and phonological language processing in bilingual subjects: preliminary findings.
The objective of the study was to explore differences in regional fMRI activation topography and lateralization between semantic and phonological tasks performed in English and Spanish in bilingual individuals. Eight bilingual (primary Spanish and secondary English-speaking) individuals performed fMRI noun-verb association and rhyming tasks in both Spanish and English. Functional dataset analysis within Statistical Parametric Mapping (SPM99) with overlay on T1-weighted anatomic images was performed. Significantly higher laterality indices were noted in the semantic tasks as compared with the phonological tasks in the anterior regions of interest comprising the frontal and superior temporal lobes. A task subtraction analysis demonstrated right hemispheric (inferior frontal gyrus and supramarginal gyrus) foci of significantly increased activation in the combined language phonological tasks compared to the combined language semantic tasks; similarly prominent right hemispheric activation was seen in the English phonological-English semantic subtraction, but the analogous Spanish task subtraction revealed no task-related differences. This divergence in activation topography between semantic and phonological tasks performed in the nonnative language, but not in the primary language, suggests that neural networks utilized for phonological and semantic language processing in the nonnative language may not be as similar as those in the primary language.
Pillai
Jay J
JJ
Department of Radiology, the Medical College of Georgia, Augusta, GA 30912, USA. jpillai@mail.mcg.edu
Araque
Julio M
JM
Allison
Jerry D
JD
Sethuraman
Sankar
S
Loring
David W
DW
Thiruvaiyaru
Dharma
D
Ison
Claro B
CB
Balan
Aparna
A
Lavin
Tom
T
D000328:Adult; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000033:anatomy & histology / Q000502:physiology*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007802:Language; D008279:Magnetic Resonance Imaging; D008297:Male; D012660:Semantics; D013067:Speech Perception / Q000502:physiology; D014936:Word Association Tests