title: An fMRI study of visual hemifield integration and cerebral lateralization.
abstract: The human brain integrates hemifield-split visual information via interhemispheric transfer. The degree to which neural circuits involved in this process behave differently during word recognition as compared to object recognition is not known. Evidence from neuroimaging (fMRI) suggests that interhemispheric transfer during word viewing converges in the left hemisphere, in two distinct brain areas, an "occipital word form area" (OWFA) and a more anterior occipitotemporal "visual word form area" (VWFA). We used a novel fMRI half-field repetition technique to test whether or not these areas also integrate nonverbal hemifield-split string stimuli of similar visual complexity. We found that the fMRI responses of both the OWFA and VWFA while viewing nonverbal stimuli were strikingly different than those measured during word viewing, especially with respect to half-stimulus changes restricted to a single hemifield. We conclude that normal reading relies on left-lateralized neural mechanisms, which integrate hemifield-split visual information for words but not for nonverbal stimuli.
authors.affiliation: University of Nevada, Reno, Department of Psychology, USA. Electronic address: lars@unr.edu.
authors.forename: Lars
authors.initials: L
authors.lastname: Strother
authors.affiliation: University of Nevada, Reno, Department of Psychology, USA.
authors.forename: Zhiheng
authors.initials: Z
authors.lastname: Zhou
authors.affiliation: University of Western Ontario, Brain and Mind Institute, Canada.
authors.forename: Alexandra K
authors.initials: AK
authors.lastname: Coros
authors.affiliation: University of Western Ontario, Brain and Mind Institute, Canada.
authors.forename: Tutis
authors.initials: T
authors.lastname: Vilis
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000000981:diagnostic imaging*; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D010100:Oxygen / Q000097:blood; D010775:Photic Stimulation; D014795:Visual Pathways / Q000000981:diagnostic imaging*; D014796:Visual Perception / Q000502:physiology*; D055815:Young Adult
chemical_list: D010100:Oxygen
keywords: Cerebral lateralization; Hemispheric transfer; Visual cortex; Word recognition; fMRI