Drifting gratings can modulate the activity of visual neurons at the temporal frequency of the stimulus. In order to characterize the temporal frequency modulation in the cat's ascending tectofugal visual system, we recorded the activity of single neurons in the superior colliculus, the suprageniculate nucleus, and the anterior ectosylvian cortex during visual stimulation with drifting sine-wav...

OBJECTIVE To evaluate the chronotropic response to exercise during immediate and late postoperative period after atrial fibrillation and mitral valve surgical treatment by different techniques. METHODS Prospective controlled clinical study of 42 patients presenting chronic AF associated mitral valve disease, who underwent surgery by the techniques of pulmonary veins isolation (n=16), Modified...

The effects of chronic dynamic exercise on myocardial beta-adrenergic and muscarinic cholinergic receptors and chronotropic sensitivity to isoproterenol were studied in 5 Yucatan miniswine. Right atrial and left ventricular biopsies, heart rate responses to isoproterenol, and maximal exercise treadmill testing were obtained before and after 10-19 weeks of treadmill running. Radioligand studies ...

This study determined whether marked hyperthermia alone or in combination with dehydration reduces the initial rate of rise in O(2) consumption (VO(2) on-kinetics) and the maximal rate of O(2) uptake (VO(2 max)) during intense cycling exercise. Six endurance-trained male cyclists completed four maximal cycle ergometer exercise tests (402 +/- 4 W) when euhydrated or dehydrated (4% body wt) with ...

This study uses the joint receive antenna selection and symbol detection (JRAS/SD) technique to simultaneously improve the bit error rate and channel capacity while reducing the cost of the radio-frequency chains in multipleinput multiple-output (MIMO) systems. Optimal antenna selection methods in the literatureare based on the criteria of maximal capacity or minimal bit error rate. Either of t...

the pathophysiology of primary benign exertional headache (eh) is not still clearly defined. some researchers have suggested an impaired vascular response as the etiology of this disorder. in this study we investigated whether there are any differences in blood pressure (bp) and heart rate (hr) of the subjects in course of the static and dynamic exercises and the treadmill stress test between t...

When angiotensin II stimulates aldosterone secretion, it causes a rapid but transient mobilization of calcium from an intracellular pool and a sustained increase in the influx of calcium in adrenal glomerulosa cells. The present studies were undertaken to determine the respective roles of the two angiotensin II-induced changes in cellular calcium metabolism in modulating events during the susta...

THE INTERPRETATION OF ELECTROCARDIOGRAPHIC CHANGES in response to exercise testing is of established value in the early detection, diagnosis, and subsequent management of coronary atherosclerotic heart disease (CAD).'` The major emphasis placed on interpretation of the exercise electrocardiogram (ECG) has, however, tended to de-emphasize the value and significance of other commonly acquired exe...

Maximal exercise heart rate (HRmax) is reduced after acclimatization to hypobaric hypoxia. The low HRmax contributes to reduce maximal cardiac output (Qmax) and may limit maximal O2 uptake (VO2max). The objective of these experiments was to test the hypothesis that the reduction in Qmax after acclimatization to hypoxia, due, in part, to the low HRmax, limits VO2max. If this hypothesis is correc...