Spectral-temporal analysis of cortical oscillations during lexical processing.

We investigated the oscillatory neural correlates of auditory lexical processing in healthy adults. Synthetic aperture magnetometry was used to characterize the timing of event-related desynchronization (ERD)/event-related synchronization (ERS) in superior temporal gyri following low-frequency and high-frequency words in contrast to nonwords. ERS and ERD responses were found with both word and nonword stimuli. Analysis of power revealed significantly elevated θ-α range (6-14 Hz) ERD in response to words compared with nonwords (left hemisphere: 390-945 ms poststimulus). Furthermore, a burst of ERS in the γ band (40-50 Hz, centered at 410 ms poststimulus) distinguished high-frequency and low-frequency words, and also displayed left-hemispheric enhancement following words. Results demonstrate a clear neural correlate of lexical access and provide a basis for further study of spectral-temporal brain activity during language processing.