Comparison of time-frequency responses and the event-related potential to auditory speech stimuli in human cortex.
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.
Department of Psychology and Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA, USA. erik@socrates.berkeley.edu
Erik
E
Edwards
Maryam
M
Soltani
Won
W
Kim
Sarang S
SS
Dalal
Srikantan S
SS
Nagarajan
Mitchel S
MS
Berger
Robert T
RT
Knight
D000161:Acoustic Stimulation / Q000379:methods; D000328:Adult; D001303:Auditory Cortex / Q000502:physiology*; D001931:Brain Mapping; D003265:Contingent Negative Variation / Q000502:physiology*; D004569:Electroencephalography; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D011930:Reaction Time / Q000502:physiology*; D013060:Speech; D013997:Time Factors; D055815:Young Adult