Dynamics of hemispheric dominance for language assessed by magnetoencephalographic imaging

Objective—The goal of the current study was to examine the dynamics of language lateralization using magnetoencephalographic (MEG) imaging, to determine the sensitivity and specificity of MEG-imaging, and to determine if MEG-imaging can become a viable alternative to the intracarotid amobarbital procedure (IAP), the current gold-standard for preoperative language lateralization in neurosurgical candidates. Methods—MEG was recorded during an auditory verb-generation task and imaging analysis of oscillatory activity was initially performed in 21 subjects with epilepsy, brain tumor, or arteriovenous malformation who had undergone IAP and MEG. Time-windows and brain regions-of-interest that best discriminated between IAP determined left or right dominant for language were identified. Parameters derived in the retrospective analysis, was applied to a prospective cohort of 14 patients and healthy controls. Results—Power decreases in the beta-frequency band were consistently observed following auditory stimulation in inferior frontal, superior temporal, and parietal cortices; similar power decreases were also seen in inferior frontal cortex prior to and during overt verb generation