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Biomedical subjects

S Svebak

Publications and source records attributed to S Svebak.

47 records · Page 3Linked to original sources
PubMed1982

The effect of a threatening context upon motivation and task-induced physiological changes.

The effect of a threatening context upon tonic task-induced physiological changes was tested in an experiment where 14 male subjects performed a continuous perceptual motor task for 150 seconds, once with and once without threat of aversive electric shock (counterbalanced order). Results indicated that task-irrelevant muscular tension increased and skin temperature decreased over the course of a task, and these gradients were steeper with threat than for the no-threat treatment. Initial heart-rate increase was marked for the threat condition. For respiration, a trend parallel to muscular gradients emerged with no-threat as contrasted with a parallel respiratory-cardiac activation with threat. Subjects' ratings on items reflecting self-perception responded to the threat manipulation, but ratings on items reflecting task perception remained unaffected.

Adult↗
PubMedDate not supplied

The effect of task difficulty and threat of aversive electric shock upon tonic physiological changes.

Thirteen subjects volunteered in an experiment which tested the relative effect of task difficulty and threat of aversive electric shock upon tonic changes in skeletal muscle (somatic) tension, respiration, heart rate (HR), and skin conductance level (SCL). They all performed two versions of a continuous perceptual-motor task (which is different from the reaction time task paradigm currently being preferred in related research), one difficult and one easy, under conditions of threat and no-threat. Electromyographic activity increased over the course of a task and, thus, showed clear physiological gradients which were steeper with the difficult task and threat. Initial HR activation was marked for the threat condition, and task difficulty added to this activation. SCL revealed a marked initial peak-response for all treatments, but was unresponsive to experimental manipulations. It was argued that a respiratory-somatic parallelism occurred during performance of both tasks for the no-threat (low effort) condition, and that threat (high effort) acted to dissolve this coupling in favour of a respiratory-cardiac parallelism.

Adult↗
PubMedDate not supplied

Low vagal tone and antral dysmotility in patients with functional dyspepsia.

Effects of acute mental stress on gastric antral motility were investigated in 23 healthy persons and 25 patients with functional dyspepsia (FD). Real-time ultrasonography of gastric antrum was recorded, after ingestion of 500 ml meat soup, during a 4-min resting period, 2.5 min of mental stress, and a 4-min recovery period. Amplitude of antral contractions was scored as a fraction of relaxed area. Motility-index was calculated as the amplitude multiplied by frequency. Measurement of skin conductance reflected sympathetic tone, and respiratory sinus arrhythmia (RSA) was calculated to index vagal tone. Antral motility was reduced by mental stress in the healthy persons, but not in FD patients. Group differences were significant for amplitude (p < 0.002) and motility-index scores (p < 0.02). Sympathetic tone increased during stress in both groups. Vagal tone was lower in the FD patients than in the healthy controls (p < 0.001). The lack of stress-related reduction of motility among patients with FD may, therefore, be a consequence of poor vagal tone.

Adolescent↗
PubMedDate not supplied

Low vagal activity as mediating mechanism for the relationship between personality factors and gastric symptoms in functional dyspepsia.

Low vagal tone may represent a mediating mechanism for relationships between personality and symptoms of functional dyspepsia (FD) through a mechanism of antral hypomotility. Twenty-one patients with FD and seventeen healthy controls completed a series of personality tests before vagal and sympathetic activity, antral motility, and abdominal symptoms were assessed in response to a laboratory task. Functional dyspepsia patients had lower scores on vagal tone (p = .054) and motility index (p = .011) in addition to the expected higher scores on epigastric discomfort (p = .002). Psychological factors explained a substantial amount of the variance in vagal activity, antral motility, and reported symptoms. Symptoms were predicted by trait anxiety (STAI-TR), depression (BDI), and neuroticism (EPQ-N). Poor vagal tone was related to neuroticism (EPQ-N). Poor motility was best explained by task-related state dysphoria (SACL-STR).

Adolescent↗