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Biomedical subjects

G Felsten

Publications and source records attributed to G Felsten.

11 recordsLinked to original sources
PubMed1992

Influences of stress and situation-specific mastery beliefs and satisfaction with social support on well-being and academic performance.

The present study examined the effects of stress and cumulative situation-specific mastery beliefs and satisfaction with social support on somatic and psychological symptomatology and academic performance of 146 college men. Stress was directly related to increased symptomatology and decreased grade point average, whereas mastery beliefs were directly associated with reduced depression and anxiety. Satisfaction with social support was related to anxiety through an interaction with mastery. Neither mastery nor satisfaction with support appeared to act as a stress-buffer through a statistical interaction with stress to moderate effects of high stress. However, earlier analysis of some of the same data showed that total stress, the best predictor of each outcome in this study, was reduced by the combination of strong situation-specific mastery beliefs and high satisfaction with support for subjects who faced many stressors. The combined findings show that situation-specific mastery beliefs reduced appraisal of stress and were associated with better psychological adjustment.

Achievement↗
PubMed1992

Why is life stress ignored in studies of 'stress' and athletic performance?

Investigations of relationships between stress and athletic performance and stress and outcomes outside of sport psychology have a parallel evolution. Each area has advanced from early attempts to find simple, strong relationships to current strategies for evaluating the influences of individual differences and situational factors on more elusive relationships. However, the most common conceptualizations of stress are very different in research on sport psychology and stress, and most studies of stress and athletic performance do not involve the influences of stress outside athletics. We propose that the approaches used by sports psychologists and stress researchers could be combined to evaluate more fully the relationships between stress and athletic performance.

Achievement↗
PubMed1991

Influences of situation-specific mastery beliefs and satisfaction with social support on appraisal of stress.

Previous research on the effects of mastery beliefs on appraisal of stress usually employed generalized measures such as locus of control and produced mixed findings, depending, in part, on whether the encounters experienced were within the domains of control assessed. The present study examined the effects of situation-specific mastery and satisfaction with social support on the appraisal of a situation's stressfulness by 147 male college students. Mastery was positively correlated with the appraisal of desirability of the situation and accounted for 36.9% of the variance. Greater satisfaction with social support was related to more positive appraisals by subjects with high mastery but with more negative appraisals by subjects with low mastery. Mastery and satisfaction with support also interacted to moderate the effects of the number of stressors experienced on total stress. For subjects who faced many stressors, those with low mastery experienced high stress regardless of their satisfaction with support, whereas those with high mastery experienced high stress if their satisfaction with support was low, but moderately low stress if satisfaction with support was high.

Adaptation, Psychological↗
PubMed1989

Responses of nucleus ambiguus neurons to arterial pressure manipulations.

Nearly 69% of nucleus ambiguus neurons in the anesthetized, artificially respired dog responded to nonpharmacological manipulations of arterial pressure (AP). All were active at resting AP, most responded robustly to increased AP, and of these, about half showed activity modulated by the respiratory cycle. Other AP-sensitive neurons fired only during the inspiratory or expiratory phase of the pump-driven respiratory cycle, and were inhibited by increased AP and excited by decreased AP.

Action Potentials↗
PubMed1987

Stimulation of the locus coeruleus decreases arterial pressure.

Unilateral microinjection of L-glutamate (L-Glu, 0.5-5 nmol) into the locus coeruleus (LC) of rats anesthetized with chloralose elicited decreases in blood pressure and heart rate. The maximal depressor response elicited by injection of L-Glu into the LC was approximately 30 mmHg, and the maximal bradycardic response was approximately 35 bpm. Microinjections into the LC of DL-homocysteic acid (1 nmol) and carbachol (1 nmol), agents which (like L-Glu) stimulate neurons within the LC, also produced depressor and bradycardic responses. Vagal blockade with methyl atropine eliminated the bradycardic response, but had no effect on the decrease in arterial pressure elicited by stimulation of neurons within the LC. Destruction of the noradrenergic neurons of the LC by local administration of 6-hydroxydopamine eliminated the cardiovascular responses elicited by injection of L-Glu or carbachol into the LC. These results are in direct contrast to the pressor response elicited by electrical stimulation of the region containing the LC. Destruction of the LC with 6-hydroxydopamine, which totally eliminated the depressor response to L-Glu, slightly potentiated the pressor response elicited by electrical stimulation of this region. Electrical stimulation of the region containing the LC has also been reported to increase plasma vasopressin levels; this response could not be reproduced by by stimulation of the LC by microinjection of L-Glu. These results indicate that stimulation of the noradrenergic neurons of the rat LC decreases arterial pressure and heart rate. Furthermore, these results suggest that the pressor response elicited by electrical stimulation of this region is not due to stimulation of neurons of the LC.

Animals↗
PubMed1987

Recordings from arterial pressure-sensitive units in the awake dog.

Recordings were made from units in or near nucleus ambiguus (NA) in the awake, drug-free dog while arterial pressure (AP) was increased and decreased nonpharmacologically by inflating occlusion cuffs that had been placed around the descending aorta and inferior vena cava, respectively. Units were recorded differentially through floating fine-wire electrodes that extended from vertically movable cannulas in a chronically implanted microdrive. Fifty-three percent of units recorded in or near NA were excited by increased AP, but were unresponsive to decreased AP. The remaining units were unresponsive to increased or decreased AP. About 25% of AP-sensitive units had activity patterns related to the cardiac cycle. AP-sensitive, cardiac cycle related units located in NA displayed several of the properties previously demonstrated for antidromically identified preganglionic parasympathetic cardiac motoneurons involved in baroreflex control of heart rate and rhythm. Recording from such neurons in the awake, neurologically intact, drug-free dog permits the fullest and most natural expression of neuro-cardiologic interactions and will allow the investigation of behavioral influences on autonomic and cardiovascular function.

Action Potentials↗
PubMed1987

Differential effect of stimulation of nucleus ambiguus on atrial and ventricular rates.

Acute experiments were performed on open-chest male mongrel dogs that were anesthetized with thiopental sodium and respired. An average of 10 penetrations per side was used to explore the rostral-caudal organization of the nucleus ambiguus (NA) and the area ventrolateral to it. Atrial pacing was performed on some trials to clarify the occurrence of atrioventricular (AV) block. In addition, the vagi were sectioned in some animals to confirm the peripheral pathway of the observed effects. Finally, the twin-pulse technique was used to classify the neurons underlying the observed effects according to their refractory periods. Stimulation in the area of the NA and lateral to it produced bradycardia and bradyarrhythmias without altering blood pressure. Stimulation of either the left or right NA produced slowing of both atrial and ventricular rates. However, slowing of the atrial rate was greatest with right NA stimulation, whereas slowing of the ventricular rate was predominant with left-side stimulation. The presence of AV block was evident from dropped QRS complexes with and without pacing. Vagotomy demonstrated that these effects were conducted by ipsilateral but not contralateral nerves. Measurement of the refractory periods showed that the neurons underlying both atrial and ventricular slowing were characteristic of B-fibers.

Analysis of Variance↗
PubMed1979

The psychophysical function: harmonizing Fechner and Stevens.

The methods of Fechner and Stevens for assessing sensation quantity usually yield different psychophysical functions even when all other factors are controlled. In this experiment, corresponding differences occurred when different features of the same sensory receptor signals were analyzed. In the visual system, the receptor potential saturated if the peak but not the area was measured; these results match visual psychophysical functions obtained with the methods of Fechner and Stevens, respectively. This result suggests that both methods are equally valid but that each method yields the particular psychophysical function appropriate for a particular kind of information processing. A novel factor in determining sensation quantity, namely the time used by the observer to make a judgment, is implicated by the data.

Animals↗