Tracking speech comprehension in space and time.
A fundamental challenge for the cognitive neuroscience of language is to capture the spatio-temporal patterns of brain activity that underlie critical functional components of the language comprehension process. We combine here psycholinguistic analysis, whole-head magnetoencephalography (MEG), the Mismatch Negativity (MMN) paradigm, and state-of-the-art source localization techniques (Equivalent Current Dipole and L1 Minimum-Norm Current Estimates) to locate the process of spoken word recognition at a specific moment in space and time. The magnetic MMN to words presented as rare "deviant stimuli" in an oddball paradigm among repetitive "standard" speech stimuli, peaked 100-150 ms after the information in the acoustic input, was sufficient for word recognition. The latency with which words were recognized corresponded to that of an MMN source in the left superior temporal cortex. There was a significant correlation (r = 0.7) of latency measures of word recognition in individual study participants with the latency of the activity peak of the superior temporal source. These results demonstrate a correspondence between the behaviorally determined recognition point for spoken words and the cortical activation in left posterior superior temporal areas. Both the MMN calculated in the classic manner, obtained by subtracting standard from deviant stimulus response recorded in the same experiment, and the identity MMN (iMMN), defined as the difference between the neuromagnetic responses to the same stimulus presented as standard and deviant stimulus, showed the same significant correlation with word recognition processes.
Pulvermüller
Friedemann
F
MRC Cognition and Brain Sciences Unit, 15 Chaucer Road, Cambridge CB2 2EF, England, UK. friedemann.pulvermuller@mrc-cbu.cam.ac.uk
Shtyrov
Yury
Y
Ilmoniemi
Risto J
RJ
Marslen-Wilson
William D
WD
D000328:Adult; D001288:Attention / Q000502:physiology*; D001309:Auditory Threshold / Q000502:physiology; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000502:physiology*; D032882:Comprehension / Q000502:physiology*; D003265:Contingent Negative Variation; D004292:Dominance, Cerebral / Q000502:physiology; D005072:Evoked Potentials, Auditory / Q000502:physiology; D005260:Female; D006801:Humans; D015225:Magnetoencephalography; D008297:Male; D009949:Orientation / Q000502:physiology*; D010700:Phonetics; D011578:Psycholinguistics; D011930:Reaction Time / Q000502:physiology; D012815:Signal Processing, Computer-Assisted; D013018:Sound Spectrography; D013063:Speech Discrimination Tests; D013067:Speech Perception / Q000502:physiology*; D013702:Temporal Lobe / Q000502:physiology; D013998:Time Perception / Q000502:physiology*