Ken-ichi Shibuya

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AIM The purpose of this study was to examine the effect of fatigue resulting from supramaximal dynamic exercise on cerebral cortex activity. METHODS Five healthy male subjects (age 24.6+/-0.4 years, body weight 62.9+/-1.1 kg, height 175.3+/-1.2 cm, and maximal O2 uptake per body mass 48.4+/-1.3 ml/kg/min) participated in this study. All subjects performed(More)
The purpose of the present study was to investigate the effect of the repetition rate of a simple movement on the magnitude of neuronal recruitment at maximal effort in humans. Nine right-handed healthy subjects [age: 27.4 +/- 4.8 yr, stature: 174.5 +/- 12.2 cm, body-weight 74.3 +/- 16.6 kg (Mean +/- SD)] participated in this study. We measured the regional(More)
This study examined cerebral deoxygenation during intermittent supramaximal exercise in six healthy male subjects (age: 27.2 +/- 0.6 years (mean +/- S.E.). The subjects performed seven times exercise at an intensity corresponding to 150% of maximal oxygen uptake (VO2max) on cycle ergometer (30 s exercise/15 s rest). Cerebral oxygenation was measured by(More)
Using near-infrared spectroscopy (NIRS) techniques, it is possible to examine bilateral motor cortex oxygenation during a static motor task. Cortical activation was assumed to be reflected by increased oxygenation. The purpose of the present study was to examine the time course of oxygenation in the bilateral motor cortex during a low-intensity handgrip(More)
The purpose of this study was to examine the effect of fatigue resulting from exhaustive pinching exercise on frontal and motor cortex activity. Eight healthy subjects (four male and four female) participated in the present study. All subjects performed at 70% of maximal voluntary contraction (MVC) pinching exercise until reaching a state of volitional(More)
Senescence of carnation petals is accompanied by autocatalytic ethylene production and wilting of the petals; the former is caused by the expression of 1-aminocyclopropane-1-carboxylate (ACC) synthase and ACC oxidase genes and the latter is related to the expression of a cysteine proteinase (CPase) gene. CPase is probably responsible for the degradation of(More)
Three ethylene receptor genes, DC-ERS1, DC-ERS2 and DC-ETR1, were previously identified in carnation (Dianthus caryophyllus L.). Here, the presence of mRNAs for respective genes in flower tissues and their changes during flower senescence are investigated by Northern blot analysis. DC-ERS2 and DC-ETR1 mRNAs were present in considerable amounts in petals,(More)
It is possible to examine bilateral primary motor cortex (M1) activation during a sustained motor task using near-infrared spectroscopy (NIRS), in which it is assumed that increased oxygenation reflects cortical activation. The purpose of this study was to examine bilateral M1 activation in response to graded levels of force production during a unilateral(More)
There are few observations of the activity of the bilateral motor cortex during prolonged exhaustive motor tasks. Knowing how the motor cortex modulates muscle fatigue or how information about fatigue affects motor cortex activities in healthy humans may help explain why fatigue is so prevalent in patients with neurological disorders. The purpose of the(More)
We examined the role of central command in static exercise-induced increase in middle cerebral artery mean blood flow velocity (V(MCA)). Eleven young female subjects performed static elbow flexion for 2 min at 30% maximal voluntary contraction without (control exercise; CONT) and with vibrations to the biceps brachii tendon (EX+VIB) in order to reduce the(More)