Word rhyming as a probe of hemispheric language dominance with functional magnetic resonance imaging

Objective: The goal of this study was to create a probe of hemispheric domi nance for language using functional magnetic resonance imaging. Background: Surgical candidates for anterior temporal lobectomy often undergo the Wada test to determine language laterality. The Wada test is invasive and canno t localize intrahemispheric language areas when surgical resection encroach es on eloquent cortex. We report the results of a stimulation paradigm that activates regions involved in motor language, language phonology, and visu al word form perception. Method: Five right-handed healthy subjects underwe nt blood oxygen level-dependent functional magnetic resonance imaging. Subj ects alternately viewed consecutive word pairs, indicating when the words r hymed, and consecutive pairs of line arrays, indicating when the arrays mat ched by responding "Yes" or "No" using a button box. Results: Subjects perf ormed both tasks with equivalent accuracy. Compared with the nonverbal cont rol task, word rhyming produced greater left-hemisphere activation than rig ht-hemisphere activation. Foci of rhyme-related activation were found in th e left Brodmann's area (BA) 44 (Broca's area), left dorsolateral prefrontal cortex (BA 9/46 and BA 8/9), left middle temporal gyrus (BA 22), and left fusiform gyrus (BA 37) in the posterior basal temporal lobe. Activation ass ociated with the control task was present in the right parietal area and in right temporal and left parietal regions. Conclusions: Subvocal word rhymi ng activates dominant perisylvian cortical regions and may be useful for de termining hemispheric language dominance and for functional mapping of lang uage cortex.