Use of a fMRI reading comprehension test supports the Wernicke-Geschwind model of written language processing

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Use Of A fMRI Reading Comprehension Test Supports The Wernicke-GeschwindModel of Written LanguageProcessing Robert B. Burr*, Jay S. TsurudaSO *Dept. of Neurosurgery t University of Utah $Dept. of Radiology $lJniversity of Utah Introduction: The Wernicke-Geschwind model proposes that language comprehension and production is the result of information transfer between cortical regions of auditory reception (Wernicke’s area; Brodmann’s 22), visual processing (Brodmann’s 17, l&19; angular gyrus) and speech production (Broca’s area; Brodmann’s 44-45) interconnected via the arcuate fasciculus. The visual pathway of this model is a well estabilished theory of written information processing. Subcomponents of this pathway include visual-spatial, orthographic, phonologic and semantic information processing regions. This visual system has been studied using a variety of cognitive paradigms. Several tMRl based tasks have in combination identified this system howeversome drawbacks to this approach are the length of time required to complete multiple imaging runs and at times, task difficult. We propose that a single reading comprehension task can identify the cortical regions involved in the visual pathway of the Wenicke-Geschwind model. Methods: Twenty-five right-handed volunteers, with negative neurologic or psychiatric histories were studied using EPI BOLD technique. fMRI was performed at 1.5 T on either G.E. Echospeed or a Picker Eclipse systems equiped with eliptical quadranture head coils. Subjects completed a reading comprehension task following a repeating “AB” design. Thirty second phases, alternated between passive gazing (Blue dot) and sentence reading. Sentences based on a third grade reading level were presented at the rate of one every three seconds. Subjects were instructed to silently read and complete sentences were the last word was left off. Data were processed on a Sun Ultra5 workstation using MEDx software and SPM technique. T-sores were calculated between the passive gaze and active reading phases. Activation maps were merged with a 3D SPGR MRI study for region analysis. Results: All subjects were able to complete the task without difficulty. Task related activation identified the various cortical regions associated with the WernickeGeschwind visual pathway model. Activated areas included Brodmann’s 17, 18, 19, the angular gyrus region, and Brodmann’s area 44-45 (Broca’s area). Sex differences reflected greater bilateral dorsal lateral prefrontal activation in females whereas, Males showed greater lateralization of activation to the left hemisphere.

Reading

Comprehension

Activation

Conclusions: Findings suggest that a reading comprehension test can activate the various cortical regions associated with the processing written language. Results support previous findings in cognitive science and fMR1 research on reading. Ease of task paradigm decreased imaging time were significant benefits gained by using a single task. Applications to cognitive neuroscience theory potential clinical care will be discussed.

This project

was supported

in part by Huntsman

Cancer

Institute

and Benning

s355

Foundation

Grants.

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