Abstract
We recorded the electrocorticogram directly from the exposed cortical surface of awake neurosurgical patients during the presentation of auditory syllable stimuli. All patients were unanesthetized as part of a language-mapping procedure for subsequent left-hemisphere tumor resection. Time-frequency analyses showed significant high-gamma (gammahigh: 70-160 Hz) responses from the left superior temporal gyrus, but no reliable response from the left inferior frontal gyrus. Alpha suppression (alpha: 7-14 Hz) and event-related potential responses exhibited a more widespread topography. Across electrodes, the alpha suppression from 200 to 450 ms correlated with the preceding (50-200 ms) gammahigh increase. The results are discussed in terms of the different physiological origins of these electrocortical signals.