Spatiotemporal dynamics of word processing in the human brain
Open Access
- 1 November 2007
- journal article
- research article
- Published by Frontiers Media SA in Frontiers in Neuroscience
- Vol. 1 (1), 185-196
- https://doi.org/10.3389/neuro.01.1.1.014.2007
Abstract
We examined the spatiotemporal dynamics of word processing by recording the electrocorticogram (ECoG) from the lateral frontotemporal cortex of neurosurgical patients chronically implanted with subdural electrode grids. Subjects engaged in a target detection task where proper names served as infrequent targets embedded in a stream of task-irrelevant verbs and nonwords. Verbs described actions related to the hand (e.g, throw) or mouth (e.g., blow), while unintelligible nonwords were sounds which matched the verbs in duration, intensity, temporal modulation, and power spectrum. Complex oscillatory dynamics were observed in the delta, theta, alpha, beta, low, and high gamma (HG) bands in response to presentation of all stimulus types. HG activity (80-200 Hz) in the ECoG tracked the spatiotemporal dynamics of word processing and identified a network of cortical structures involved in early word processing. HG was used to determine the relative onset, peak, and offset times of local cortical activation during word processing. Listening to verbs compared to nonwords sequentially activates first the posterior superior temporal gyrus (post-STG), then the middle superior temporal gyrus (mid-STG), followed by the superior temporal sulcus (STS). We also observed strong phase-locking between pairs of electrodes in the theta band, with weaker phase-locking occurring in the delta, alpha, and beta frequency ranges. These results provide details on the first few hundred milliseconds of the spatiotemporal evolution of cortical activity during word processing and provide evidence consistent with the hypothesis that an oscillatory hierarchy coordinates the flow of information between distinct cortical regions during goal-directed behavior.Keywords
This publication has 72 references indexed in Scilit:
- Phase Patterns of Neuronal Responses Reliably Discriminate Speech in Human Auditory CortexNeuron, 2007
- High Gamma Power Is Phase-Locked to Theta Oscillations in Human NeocortexScience, 2006
- Neuronal Oscillations Enhance Stimulus Discrimination by Ensuring Action Potential PrecisionPLoS Biology, 2006
- Sparse time-frequency representationsProceedings of the National Academy of Sciences of the United States of America, 2006
- Phase/amplitude reset and theta–gamma interaction in the human medial temporal lobe during a continuous word recognition memory taskHippocampus, 2005
- Listening to speech activates motor areas involved in speech productionNature Neuroscience, 2004
- Interneuron Diversity series: Inhibitory interneurons and network oscillations in vitroTrends in Neurosciences, 2003
- Differential activation of right and left posterior sylvian regions by semantic and phonological tasks: a positron-emission tomography study in normal human subjectsNeuroscience Letters, 1994
- Event-related brain potentials during natural speech processing: effects of semantic, morphological and syntactic violationsCognitive Brain Research, 1993
- Regional response differences within the human auditory cortex when listening to wordsNeuroscience Letters, 1992