Toshiaki Imada

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Discriminative responses to tones, harmonics, and syllables in the left hemisphere were measured with magnetoencephalography in neonates, 6-month-old infants, and 12-month-old infants using the oddball paradigm. Real-time head position tracking, signal space separation, and head position standardization were applied to secure quality data for source(More)
Historic theories of speech perception (Motor Theory and Analysis by Synthesis) invoked listeners' knowledge of speech production to explain speech perception. Neuroimaging data show that adult listeners activate motor brain areas during speech perception. In two experiments using magnetoencephalography (MEG), we investigated motor brain activation, as well(More)
The present study investigated whether the human mirror-neuron system exhibits gender differences. Neuromagenetic mu (approximately 20 Hz) oscillations were recorded over the right primary motor cortex, which reflect the mirror neuron activity, in 10 female and 10 male participants while they observed the videotaped hand actions and moving dot. In(More)
Linguistic experience alters an individual's perception of speech. We here provide evidence of the effects of language experience at the neural level from two magnetoencephalography (MEG) studies that compare adult American and Japanese listeners' phonetic processing. The experimental stimuli were American English /ra/ and /la/ syllables, phonemic in(More)
The present study used magnetoencephalography (MEG) to examine perceptual learning of American English /r/ and /l/ categories by Japanese adults who had limited English exposure. A training software program was developed based on the principles of infant phonetic learning, featuring systematic acoustic exaggeration, multi-talker variability, visible(More)
The mental rotation task has been reported to activate the human parietal and extra-striate areas, based on the results of fMRI and PET analysis. In the present study, we investigated the dynamic properties of the distributed cortical activity related to mental rotation processes at high temporal resolution by means of brain magnetic field measurements and(More)
Magnetoencephalography (MEG) detects the brain's magnetic fields as generated by neuronal electric currents arising from synaptic ion flow. It is noninvasive, has excellent temporal resolution, and it can localize neuronal activity with good precision. For these reasons, many scientists interested in the localization of brain functions have turned to MEG.(More)
In this study, behavioral and brain measures were taken to assess the effects of training a Japanese adult subject to perceptually distinguish English /l/ and /∞/. Behavioral data showed significant improvement in identifying both trained and untrained speech stimuli. Correspondingly, neuromagnetic results showed enhanced mismatch field responses in the(More)
Due to the rapid anatomical changes that occur within the brain structure in early human development and the significant differences between infant brains and the widely used standard adult templates, it becomes increasingly important to utilize appropriate age- and population-specific average templates when analyzing infant neuroimaging data. In this study(More)
Behavioral studies show that bilinguals are slower and less accurate when performing mental calculation in their nondominant (second; L2) language than in their dominant (first; L1) language. However, little is known about the neural correlates associated with the performance differences observed between bilinguals' 2 languages during arithmetic processing.(More)