"Tracking of the speech envelope by neural activity during speech production is not limited to Broca's area in the dominant frontal lobe"

We cross-correlated the electric cortical activity of eleven patients undergoing awake neurosurgical operations with the sound envelope of their utterances. We found that in the dominant frontal lobe the differences in the timing of the maximum of the cross-correlations calculated from the electrical activity of electrodes overlaying non-Broca's areas and those overlaying Broca's area were not constant. Our findings suggest that sound correlated activity during language generation is present in multiple areas of the frontal lobe whose activity is not reducible to a simple hierarchical model