Antecedent Stress Research Articles

Seasonal changes in the spatial distribution of phytoplankton in small, temperate-zone lakes

Seasonal sampling across two small lakes shows that phytoplankton patchiness is greatly enhanced during winter ice-cover relative to the open-water seasons of exposure to wind stress and rapid turbulent mixing. A fundamental property of plankton populations is their spatial heterogeneity or patchiness. Phytoplankton patchiness can result from spatial variations of biological processes such as growth, grazing, regulated buoyancy and vertical migration (e.g. Reynolds, 1984; Mackas et al., 1985) or from advective transports (George and Edwards, 1976), and it is disrupted by turbulent mixing. These processes are dynamic, so we expect temporal variability of phyto- plankton patchiness to accompany fluctuations in physical and biological processes across a spectrum of time scales. For example, fluctuations in the wind stress across small lakes can produce measurable change in the spatial distribution of phytoplankton, at time scales of: hours, associated with the passage of cold fronts (Stauffer, 1982); days, from the cumulative effects of antecedent wind stress over periods of 1-10 days (Small, 1963); and weeks, associated with events of enhanced vertical mixing from weather systems, which have 10-20 days periodicity (Trimbee and Harris, 1983). These observations demonstrate a dynamic coupling between the input of turbulent kinetic energy from wind and the pattern of phytoplankton spatial distribution, operating at time scales of weeks or less. Can this generality be extended to longer time scales? For example, if phytoplankton spatial patterns are responsive to hourly- daily fluctuations in wind stress, then we might expect very large changes in the distribution of phytoplankton when temperate lakes freeze over and become isolated, for months, from the input of wind energy. To test this hypothesis we mapped phytoplankton biomass (as chlorophyll a concentration) seasonally within two small lakes situated in the glacial terrain of

The Psychoneuroendocrinology of Functional Hypothalamic Amenorrhea

Women with functional hypothalamic amenorrhea display multiple neuroendocrine aberrations suggestive of altered central neurotransmission. The role of antecedent stress as an explanation for both the neurochemical changes and the dysfunctional behavior of these women is examined by utilizing concepts provided by the animal model of inescapable shock and the human condition of post traumatic stress disorder.

Panic disorder: Description, conceptualization, and implications for treatment

This paper reviews the Panic Disorder from diagnostic, clinical, and psychophysiological vantage points and concludes in suggestions for therapeutic intervention. The Panic Disorder is characterized by the repetitive onset of acute panic attacks. Evidence suggests that phasic panic anxiety is distinct from tonic, generalized anxiety, with each type having different treatment requirements. An integrated psychophysiological model incorporating cognitive appraisal theory and interoceptive conditioning theory was developed to conceptualize the panic attack. Stated briefly, stressful conditions or the perception of threat in panic patients elicit autonomic hyperactivity. Through a recurrent feedback loop, these aversive sensations become interoceptive conditional stimuli which elicit further anxiety responses and perceptions of threat. The development and implementation of adaptive coping skills is impeded by high physiological arousal, cognitive disorientation, and behavioral avoidance. The self-appraisal of inadequate coping skills intensifies anticipatory anxiety, further feeding into the cycle of panic escalation. This model suggests three fronts for intervention: (1) alleviating the antecedent stresses and conflicts which result in panic, (2) directly suppressing the physiological responses associated with panic, and (3) reducing the panic-maintaining anticipatory fear of panic through the training of cognitive and behavioral coping skills.

Acute and chronic stress effects on open field activity in the rat: Implications for a model of depression

The initial activity of a rat placed in novel surroundings (i.e., open field activity) has been taken as an indicator of its emotional state. We have investigated the effects of immediately antecedent stress upon open field activity in comparison with basal (i.e., unstressed) activity, and additionally, the effects of a history of chronic stress upon the above behavioral patterns. Acute exposure to a non-traumatic, non-debilitating stress (noise and light) consistently increased activity in comparison with basal activity. A history of chronic stress on the other hand reduced basal activity from control levels, and eliminated the activation response to acute stress. This lack of acute activation may bear some resemblance to depression on several grounds. Behaviorally it represents a “refractory loss of interest”. Also, chronically stressed rats showed endocrine changes similar to those seen in human depressives. Finally, antidepressant treatment with the monoamine oxidase inhibitor pargyline restored the ability of chronically stressed rats to respond actively to stress.

A comparative study of reactive psychosis and acute psychosis without precipitating stress.

A study was carried out to compare the antecedent factors, phenomenology, treatment required and prognosis in 30 cases of Reactive Psychosis and 30 cases of Acute Psychosis without antecedent stress, matched on age and sex. Both groups were followed up for 7 months. It was found that the two groups differed markedly on several dimensions: The Reactive Psychotics had more hysterical and affective features, more vulnerable personality, higher stress experience in their life prior to illness and relatively better prognosis compared to the Acute Psychotics. The difference still remained when those in either of the groups who at the end of the follow-up turned out to be schizophrenics or suffering from affective disorder were excluded from analysis.

The effects of relaxation instructions on drinking behavior in the presence of stress

Previous research indicates that antecedent stress is associated with increased alcohol consumption. The present study examined the influence of different treatments following threatened exposure to a public speaking situation on both drinking style measures and amount consumed in an ad lib drinking assessment session. The treatments included relaxation instructions, a sensitization or stress-enhancing treatment, and an attention-refocusing or neutral control. Significant differences in poststress drinking rates and amount consumed between the stress-relaxation and stress-sensitization groups were found. The data indicate that relaxation is an effective procedure for attenuating the impact of stress on quantity and style of drinking.

Self-management of spastic colitis

Semi-automated training in behavioural self-management for a 37-yr-old male who suffered approximately three spastic colitis attacks per week was carried out in three stages over a period of 52 weeks including two follow-ups. Stage One involved training the client in problem analysis and the self-recording and monitoring of antecedent stress events which appeared to be precipitating the attacks of spastic colitis. Stage Two involved training in muscle relaxation to counter the effects of stress events on the physical system. Stage Three focused on training the client to modify both his environment and his reactions to intrusive cognitions associated with academic-related activities. Following Stage Two there was a steady decline in colitis attack frequency which accelerated sharply following Stage Three training. The client reported that only three colitis attacks had occurred during the 32 week follow-up periods.