title: Frequency-dependent spatiotemporal distribution of cerebral oscillatory changes during silent reading: a magnetoencephalograhic group analysis.
abstract: The frequency profiles and time courses of oscillatory changes when reading words are not fully understood, although there have been many reports that oscillatory dynamics reflect local brain function. In order to clarify oscillatory dynamics, we investigated the frequency and spatiotemporal distributions of neuromagnetic activities during silent reading of words in 23 healthy subjects. Individual data were divided into the following frequency bands: theta (5-8 Hz), alpha (8-13 Hz), beta (13-25 Hz), low gamma (25-50 Hz), and high gamma (50-100 Hz), and were analyzed by synthetic aperture magnetometry (SAM). The time window was consecutively moved in steps of 50 ms. Group analysis was performed to delineate common areas of brain activation. A transient power increase in the theta band occurred first in the bilateral occipital cortices, and then rapidly propagated to the left temporo-occipital areas, left inferior and middle frontal gyri, bilateral medial prefrontal cortices, and finally to the left anterior temporal cortices, which possibly reflects a serial cognitive process. This serial propagation of the transient power increase in the theta band was followed by sustained power decreases in the alpha, beta and low gamma bands. These results suggest that the transient power increase in the theta bands may be associated with priming and propagation of local activities, while sustained power decreases in the alpha, beta and low gamma bands reflect parallel neural processes related to silent reading words. Our results showed a relationship between frequency bands of oscillatory changes and locations. This may have implications in the relationship between frequency bands and functions.
authors: Department of Neurosurgery, Osaka University Medical School, Suita, Osaka, Japan.
authors: Tetsu
authors: T
authors: Goto
authors: Masayuki
authors: M
authors: Hirata
authors: Yuka
authors: Y
authors: Umekawa
authors: Takufumi
authors: T
authors: Yanagisawa
authors: Morris
authors: M
authors: Shayne
authors: Youichi
authors: Y
authors: Saitoh
authors: Haruhiko
authors: H
authors: Kishima
authors: Shirou
authors: S
authors: Yorifuji
authors: Toshiki
authors: T
authors: Yoshimine
mesh_terms: D000328:Adult; D001921:Brain / Q000502:physiology*; D001931:Brain Mapping / Q000379:methods*; D005260:Female; D007839:Functional Laterality; D006801:Humans; D015225:Magnetoencephalography / Q000379:methods*; D008297:Male; D009482:Neurophysiology / Q000379:methods; D011932:Reading; D012016:Reference Values; D013647:Task Performance and Analysis; D013702:Temporal Lobe / Q000502:physiology; D055815:Young Adult