Spectro-temporal correlates of lexical access during auditory lexical decision.
Lexical access during speech comprehension comprises numerous computations, including activation, competition, and selection. The spatio-temporal profile of these processes involves neural activity in peri-auditory cortices at least as early as 200 ms after stimulation. Their oscillatory dynamics are less well understood, although reports link alpha band de-synchronization with lexical processing. We used magnetoencephalography (MEG) to examine whether these alpha-related oscillations reflect the speed of lexical access, as would be predicted if they index lexical activation. In an auditory semantic priming protocol, monosyllabic nouns were presented while participants performed a lexical decision task. Spatially-localizing beamforming was used to examine spectro-temporal effects in left and right auditory cortex time-locked to target word onset. Alpha and beta de-synchronization (10-20 Hz ERD) was attenuated for words following a related prime compared to an unrelated prime beginning about 270 ms after stimulus onset. This timing is consistent with how information about word identity unfolds incrementally in speech, quantified in information-theoretic terms. These findings suggest that alpha de-synchronization during auditory word processing is associated with early stages of lexical access.
University of Michigan, Department of Linguistics, United States. Electronic address: jobrenn@umich.edu.
Jonathan
J
Brennan
University of Pennsylvania, Department of Linguistics, United States; The Children's Hospital of Philadelphia, Radiology, United States.
Constantine
C
Lignos
University of Pennsylvania, Department of Linguistics, United States.
David
D
Embick
University of Pennsylvania, Department of Linguistics, United States; The Children's Hospital of Philadelphia, Radiology, United States.
Timothy P L
TP
Roberts
D000328:Adult; D000513:Alpha Rhythm / Q000502:physiology; D001303:Auditory Cortex / Q000502:physiology*; D001611:Beta Rhythm / Q000502:physiology; D032882:Comprehension / Q000502:physiology*; D019277:Entropy; D005260:Female; D065818:Gamma Rhythm / Q000502:physiology; D006801:Humans; D015225:Magnetoencephalography / Q000379:methods; D008297:Male; D008875:Middle Aged; D060865:Repetition Priming / Q000502:physiology; D013060:Speech / Q000502:physiology; D013067:Speech Perception / Q000502:physiology*; D013826:Theta Rhythm
Lexical access; Lexical decision; MEG; Neural oscillations; Semantic priming; Speech; Synthetic Aperture Magnetometry