Mitsuaki Yamamoto

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Orexin, a hypothalamic neuropeptide, has been revealed to be involved in sleep regulation. To elucidate functions of orexin in brainstem sleep regulation mechanism, we examined the effects of orexin applied from micropipettes with air pressure on neurones in and around the laterodorsal tegmental nucleus (LDT). In five of seven cholinergic neurones and six(More)
Exposure of cells to cadmium (Cd) is known to stimulate the expression of various types of genes. These changes in gene expression are presumed to be related to the cellular response to Cd toxicity. To better understand the mechanisms related to Cd toxicity, suppression subtractive hybridization was carried out on COS-7 cells (African green monkey kidney(More)
The present study examined the correlations between the dynamics of hippocampal theta waves and pontine waves (P waves) and rapid eye movements (REMs) densities during REM sleep. Theta wave peak frequency and theta amplitude were estimated as the parameters of theta wave dynamics in each 3s segment. The peak frequency and theta amplitude were positively(More)
Based upon our previous results in cats, we hypothesized that neurons in the central processor systems of the brain generally exhibit state-dependent dynamics alternation of slow fluctuations in spontaneous activity during sleep. To test the validity of this hypothesis across species, we recorded single neuronal activity during sleep from the(More)
Severe chronic active Epstein-Barr virus (EBV) infection is a lymphoproliferative disease characterized by extremely high antibody titers to EBV, fever, lymphadenopathy, hepatosplenomegaly, and pancytopenia, without any prior immunological abnormality. A spontaneous lymphoblastoid cell line was established from a 4-year-old boy with severe chronic active(More)
To clarify the stochast properties of the maintained impulse activity of the central nervous system, we proposed a measure of statistical dependency on the basis of Shannon's entropy. This measure could provide the Markov properties of the neural impulse sequences, representing the necessary and sufficient condition for the statistical dependence. The order(More)
The study demonstrated that ponto-geniculo-occipital (PGO) waves are phase-locked with hippocampal theta-waves during rapid eye movement (REM) sleep. A possible mechanism for influencing a PGO wave generator by hippocampal theta-waves was hypothesized. The generator is known to receive afferent inputs such as auditory input. To test this hypothesis, the(More)
In transmeridian flights, photic and nonphotic entrainment mechanisms are expected to interact dynamically in the human circadian system. In order to simulate the reentrainment process of the circadian rhythms, the photic entrainment mechanism was introduced to our previous model, which consisted of three coupled oscillators. Regardless of flight direction,(More)
We investigated the temporal relationship between hippocampal theta waves and ponto-geniculo-occipital waves (PGO) during rapid eye movement sleep (REM sleep) in cats. In addition, we analyzed the relationship between hippocampal theta waves and PGO as elicited by tone stimulus (PGO(E)) in order to quantitively characterize the PGO wave generator mechanism.(More)