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Predictability, control, and the pituitary-adrenal response in rats
Journal of Comparative and Physiological Psychology
|June 1, 1982
Summary
Predictability of shock influences the timing, not the amount, of stress hormone release in rats. Stress hormone responses are modulated by perceived control, even when control is not directly linked to the stressor.
Area of Science:
- Neuroscience
- Endocrinology
- Animal Behavior
Background:
- The pituitary-adrenal axis is a key stress response system.
- Predictability of a stressor can alter its impact on physiological responses.
Purpose of the Study:
- To investigate how signaled versus unsignaled shock affects pituitary-adrenal activity in rats.
- To explore the role of perceived control in modulating stress responses.
Main Methods:
- Five experiments compared plasma corticosterone levels under signaled and unsignaled shock conditions.
- Behavioral baselines and varied blood sampling times were employed.
- Rats were used as the experimental model.
Main Results:
- No significant differences in terminal corticosterone levels were found between signaled and unsignaled shock groups in most experiments.
- A signaled shock produced elevated steroid levels when sampled before the shock, suggesting a temporal effect.
- The presence of a behavioral control baseline modulated the effects of predictability on steroid levels.
Conclusions:
- The impact of predictability on stress hormones is primarily temporal, not quantitative.
- Perceived control significantly modulates the pituitary-adrenal response to stressors.
- The concept of control extends beyond direct stimulus prediction.