MEG localization of cortical activity during language processing utilizing mr-focuss and coherence source imaging

Objective: Demonstrate the noninvasive localization of cognitive cortical areas involved in picture naming using magnetoencephalography (MEG) Determine the quality of the Columbia Visual Naming Test (CVNT) for widespread use and whether it challenges older language processing paradigms To utilize the innovative new Coherence Source Imaging (CSI) to understand the coherence patterns between cortical areas during picture naming Background: MEG has been used for cortical mapping. CVNT has been used for identifying language processing areas. CSI measures the distribution of source amplitudes and frequencies of imaged activity in the brain in order to measure the connectivity of different areas of the brain during a certain task. However, CSI has never been utilized to analyze the processing of picture naming in the brain. Design/Methods: MEG data was collected during a CVNT for 14 normal English-speaking subjects. MEG data were forward and backward filtered 3 to 50 Hz. Artifacts were then filtered out. MRI was rescaled to create a cortical model for each student. A forward model was created for each subject to overlay the MEG scan onto the cortical model. An evoked solution was created using MR-FOCUSS CSI solution was created using MEG Tools Statistical analysis was performed using a boot strapping method A histogram quantified the number of sites in coherence Results: The evoked results produced a significantly more precise paradigm suggesting the high quality of CVNT to elicit cortical responses in investigating language processing. The results of the asymmetry index further proved the left hemispheric dominance paradigm and are further supported by the results of the CSI. Conclusions: The time course of neuronal language processing can be imaged noninvasively with millisecond resolution with MEG, analyzed through MR-FOCUSS technique, and that CSI provides a valuable technique to confirm and find areas of coherence in the brain to determine the validity of the language processing paradigm