Biomedical subjects

Norihito Yamada

Publications and source records attributed to Norihito Yamada.

3 recordsLinked to original sources

PubMed2006

Effect of YM872, a selective and highly water-soluble AMPA receptor antagonist, in the rat kindling and rekindling model of epilepsy.

We examined antiepileptogenic and anticonvulsant effects of [2,3-dioxo-7-(1H-imidazol-1-yl)-6-nitro-1,2,3,4-tetrahydro-1-quinoxalinyl]-acetic acid monohydrate (YM872), a potent and highly water-soluble alpha-amino-3-hydroxy-5-methyl-isoxazole-4-propionic acid (AMPA) receptor antagonist, in the rat amygdala kindling model of epilepsy. Administration of YM872 significantly suppressed fully kindled seizures. Daily pretreatment with YM872 markedly retarded development of kindling during drug sessions. We also used the rekindling method to investigate the antiepileptogenic effect of YM872 in an attempt to differentiate between true and false effects in the conventional method of daily administration. The results using the rekindling method suggested that the effect of YM872 was truly antiepileptogenic, indicating its possible clinical usefulness as an antiepileptogenic drug. We also affirmed the importance of AMPA receptors in the seizure expression mechanism and development of kindling-induced epileptogenesis.

Animals↗

PubMed2006

Analysis of magnetic source localization of P300 using the multiple signal classification algorithm.

The authors studied the localization of P300 magnetic sources using the multiple signal classification (MUSIC) algorithm. Six healthy subjects (aged 24-34 years old) were investigated with 148-channel whole-head type magnetencephalography using an auditory oddball paradigm in passive mode. The authors also compared six stimulus combinations in order to find the optimal stimulus parameters for P300 magnetic field (P300m) in passive mode. Bilateral MUSIC peaks were located on the mesial temporal, superior temporal and parietal lobes. Interestingly, all MUSIC peaks in these regions emerged earlier in the right hemisphere than in the left hemisphere, suggesting that the right hemisphere has predominance over the left in the processing activity associated with P300m. There were no significant differences among the six stimulus combinations in evoking those P300m sources. The results of the present study suggest that the MUSIC algorithm could be a useful tool for analysis of the time-course of P300m.

Adult↗

PubMed2006

Medial profrontal cortex and anterior cingulate cortex in the generation of alpha activity induced by transcendental meditation: a magnetoencephalographic study.

Previous EEG studies have shown that transcendental meditation (TM) increases frontal and central alpha activity. The present study was aimed at identifying the source of this alpha activity using magnetoencephalography (MEG) and electroencephalography (EEG) simultaneously on eight TM practitioners before, during, and after TM. The magnetic field potentials corresponding to TM-induced alpha activities on EEG recordings were extracted, and we attempted to localize the dipole sources using the multiple signal classification (MUSIC) algorithm, equivalent current dipole source analysis, and the multiple spatio-temporal dipole model. Since the dipoles were mapped to both the medial prefrontal cortex (mPFC) and anterior cingulate cortex (ACC), it is suggested that the mPFC and ACC play an important role in brain activity induced by TM.

Adult↗