Kyuichi Niizeki

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The nature of entrainment between cardiac and locomotor rhythms was investigated while normal human subjects walked or ran on a treadmill. To detect the incidence of entrainment occurrence, the phase relationships among cardiac, respiratory, and locomotor rhythms were analyzed. The phase relationship between heartbeats and gait signals showed that(More)
To determine the effects of muscle pump function on cardiac autonomic activity in response to quiet standing, we simulated the muscle pump effect by rhythmic lower-leg cuff inflation (RCI) with four cuff pressures of 0 (sham), 40, 80, and 120 mmHg at 5 cycles/min. The R-R interval (RRI) and beat-to-beat blood pressure (BP) were acquired in healthy subjects(More)
A multi-spectral diffuse reflectance imaging method based on a single snap shot of Red-Green-Blue images acquired with the exposure time of 65 ms (15 fps) was investigated for estimating melanin concentration, blood concentration, and oxygen saturation in human skin tissue. The technique utilizes the Wiener estimation method to deduce spectral reflectance(More)
Interactions are described of central origin between respiratory, cardiac and stepping rhythms during fictive locomotion in paralyzed, vagotomized, and decerebrated cats. Fictive locomotion was induced by tonic electrical stimulation of the mesencephalic locomotor region (MLR). The coherence between heart beat fluctuation, the efferent discharges of the(More)
Interactions between locomotor, respiratory, and cardiac rhythms were investigated in human subjects (n = 11) walking on a treadmill. Investigation of the phase relationship between heart rate and gait signals revealed that cardiac rhythms were entrained to locomotor rhythms when both frequencies were close to an integer ratio. Coherence spectra were(More)
The purpose of this study was to determine whether the transfer function characteristics of the respiratory CO2 control system differs according to whether the CO2 administration method is constant fraction (CF) or constant inflow (CFlow). Ventilatory responses to CO2 changes were measured in seven healthy subjects during random PETCO2 perturbation by the(More)
Fictive locomotion was evoked by stimulation of the mesencephalic locomotor region (MLR) in immobilized, vagotomized and decerebrate cats. The coherence between heart beat fluctuation and efferent discharges of the hindlimb nerve was used to evaluate the strength of the coupling between the cardiac and locomotor rhythms during MLR-elicited fictive(More)
The present study analyzed whether the phase coherency (λ) of respiratory sinus arrhythmia (RSA) is altered by food ingestion in healthy young subjects. After 5min of resting control, 13 healthy volunteers were asked to eat a solid meal with access to water at their own pace, followed by 5min of the postprandial state. The R-R interval (RRI), beat-to-beat(More)
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