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Language processes during overt and covert speech in a simulated driving task

Authors: S. M. Bowyer, J. E. Moran, S. Seaman, R. A. Young, John M. Sullivan, R. Farjam, N. Tepley, L. Hsieh.

We used MEG to explore the neural correlates of language processing in a simulated driving environment. Functional MRI and MEG studies require subjects to remain still and not move their mouths, unlike real on-road driving conditions. MEG was used to identify the cortical regions engaged in language processing during hands-free overt (out loud) and covert (silent) cell phone conversations during simulated driving. Subjects viewed a real-world driving video and responded (foot pedal) to red dot stimuli (visual events) presented either centrally or peripherally on the driving scene, while performing a lane tracking task (arrow on screen) with right fore and middle fingers. We termed this condition, with no-speech, as Task 1. Other conditions involved performing Task 1 while the subject spoke out loud (Task 2) or silently (Task 3). MEG data were collected for 8 minutes for each task. Coherence analysis compared activations of Broca-s and Wernicke-s areas in the three conditions. The inferior frontal gyrus (Broca-s) and the superior temporal gyrus (Wernicke-s) language areas were activated similarly in the overt and covert conditions. These activations were significantly different from the no-speech condition where little or no cortical activation was detectable in these language processing areas. The use of MEG to investigate neural processing during simulated driving tasks appears quite promising, since the use of covert speech instead of overt speech can provide similar cortical activation patterns, in the movement-sensitive MEG environment. This study hopes to expand automotive safety technology, which may help reduce traffic accidents/crashes by better understanding how the brain processes information in multi-tasking environments, in turn leading to improved designs of in-vehicle technologies.

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