Functional anatomy of intra- and cross-modal lexical tasks.
Functional magnetic resonance imaging (fMRI) was used to examine lexical processing in normal adults (20-35 years). Two tasks required only intramodal processing (spelling judgments with visual input and rhyming judgments with auditory input) and two tasks required cross-modal processing between phonologic and orthographic representations (spelling judgments with auditory input and rhyming judgments with visual input). Each task led to greater activation in the unimodal association area concordant with the modality of input, namely fusiform gyrus (BA 19, 37) for written words and superior temporal gyrus (BA 22, 42) for spoken words. Cross-modal tasks generated greater activation in posterior heteromodal regions including the supramarginal and angular gyri (BA 40, 39). Cross-modal tasks generated additional activation in unimodal areas representing the target of conversion, superior temporal gyrus for visual rhyming and fusiform gyrus for auditory spelling. Our findings suggest that the fusiform gyrus processes orthographic word forms, the superior temporal gyrus processes phonologic word forms, and posterior heteromodal regions are involved in the conversion between orthography and phonology.
Booth
James R
JR
Department of Communication Sciences and Disorders, Northwestern University, Evanston, Illinois, USA.
Burman
Douglas D
DD
Meyer
Joel R
JR
Gitelman
Darren R
DR
Parrish
Todd B
TB
Mesulam
M Marsel
MM
D000328:Adult; D001921:Brain / Q000033:anatomy & histology* / Q000502:physiology*; D001931:Brain Mapping; D005260:Female; D006801:Humans; D007802:Language; D008279:Magnetic Resonance Imaging; D008297:Male; D011597:Psychomotor Performance / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology; D011932:Reading; D013067:Speech Perception / Q000502:physiology