Heart rate reactivity as a predictor of neuroendocrine responses to aversive and appetitive challenges

The present paper examines the neuroendocrine influences of aversive and reward incentives (noise and shock versus monetary bonuses) presented during reaction time tasks administered to 71 healthy men (ages 21 to 35) classified as being high (N = 30) or low (N = 41) in heart rate reactivity. High heart rate reactivity was defined as a peak heart rate increase or greater than 19 bpm to a cold pressor test administered on a different day. Independent groups of subjects worked on one of two visual reaction time tasks: either to avoid exposure to noise (115-dBA bursts) and shock (3.5 mV, 2 sec), or to earn monetary bonuses ($0.50). High heart rate reactors showed significant plasma norepinephrine rises from baseline both to aversive incentives and to reward, although they showed significant cortisol responses only during aversive incentives. In contrast, the low heart rate reactors were unresponsive in cortisol and norepinephrine during either type of incentive. These results support psychoendocrine models which view the norepinephrine response as being nonspecifically related to expenditure of effort regardless of the emotional connotations of the challenge, while cortisol is seen as being secreted primarily during periods of distress. The present data further suggest that cardiovascular reactivity is linked to neuroendocrine reactivity, possibly within the central nervous system.