Reward anticipation buffers neuroendocrine and cardiovascular responses to acute psychosocial stress in healthy young adults

How is variability in physiological responses to social stress related to punishment and reward sensitivities? Preliminary findings from the revised reinforcement sensitivity theory of personality perspective

OBJECTIVE

Although personality traits are assumed to have biological/physiological foundations, research has yielded mixed evidence regarding the relationship between personality and physiological stress responses. Moreover, the field has often overlooked the contemporary neuroscience-based personality approach, known as the Reinforcement Sensitivity Theory (RST) of Personality, in stress research.

METHOD

The present study examined the relationship between the revised RST's personality dimensions and heart rate and skin conductance level (SCL) in response to the Trier Social Stress Test in a sample of 61 healthy university students.

RESULTS

Piecewise latent growth curve analysis controlling for the participants' current life stress, smoking use, and caffeine intake revealed that individuals with higher behavioral inhibition exhibited higher physiological reactivity, whereas those with high reward sensitivity showed smaller heart rate reactivity. The behavioral disengagement facet of the behavioral inhibition scale was associated with reduced sympathetic arousal during the stress task. Additionally, reward interest was associated with a larger recovery of SCL.

CONCLUSION

Results were generally in line with the revised theory. The study findings were discussed within the paradigm of the approach-avoidance conflict and highlighted the importance of reward sensitivity in stress resilience.

Stressor-Specific Sex Differences in Amygdala-Frontal Cortex Networks

Females and males differ in stress reactivity, coping, and the prevalence rates of stress-related disorders. According to a neurocognitive framework of stress coping, the functional connectivity between the amygdala and frontal regions (including the dorsolateral prefrontal cortex (dlPFC), ventral anterior cingulate cortex (vACC), and medial prefrontal cortex (mPFC)) plays a key role in how people deal with stress. In the current study, we investigated the effects of sex and stressor type in a within-subject counterbalanced design on the resting-state functional connectivity (rsFC) of the amygdala and these frontal regions in 77 healthy participants (40 females). Both stressor types led to changes in subjective ratings, with decreasing positive affect and increasing negative affect and anger. Females showed higher amygdala-vACC and amygdala-mPFC rsFC for social exclusion than for achievement stress, and compared to males. Whereas a higher amygdala-vACC rsFC indicates the activation of emotion processing and coping, a higher amygdala-mPFC rsFC indicates feelings of reward and social gain, highlighting the positive effects of social affiliation. Thus, for females, feeling socially affiliated might be more fundamental than for males. Our data indicate interactions of sex and stressor in amygdala-frontal coupling, which translationally contributes to a better understanding of the sex differences in prevalence rates and stress coping.

Reward sensitivity modulates the brain reward pathway in stress resilience via the inherent neuroendocrine system

In the previous 10 years, researchers have suggested a critical role for the brain reward system in stress resilience. However, no study has provided an empirical link between activity in the mesostriatal reward regions during stress and the recovery of cortisol stress response. Moreover, although reward sensitivity as a trait has been demonstrated to promote stress resilience, it remains unclear whether it modulates the brain reward system in stress resilience and how this effect is achieved by the inherent neuroendocrine system. To investigate these uncertainties, 70 young adults were recruited to participate in a ScanSTRESS task, and their brain imaging data and saliva samples (for cortisol assay) were collected during the task. In addition, we assessed reward sensitivity, cortisol awakening response, and intrinsic functional connectivity of the brain in all the participants. We found that left putamen activation during stress exposure positively predicted cortisol recovery. In addition, reward sensitivity was positively linked with activation of the left putamen, and this relationship was serially mediated by the cortisol awakening response and right hippocampus-left inferior frontal gyrus intrinsic connectivity. These findings suggest that reward sensitivity modulates reward pathways in stress resilience through the interplay of the diurnal stress response system and network of the hippocampus-prefrontal circuitry. Summarily, the current study built a model to highlight the dynamic and multifaceted interaction between pertinent allostatic factors in the reward-resilience pathway and uncovered new insight into the resilience function of the mesostriatal reward system during stress.

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Cortisol recovery can be predicted by activation of the left putamen in stress.

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Activation of the left putamen was positively linked with reward sensitivity.

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This relationship was serially mediated by the cortisol awakening response and right hippocampus-left inferior frontal gyrus intrinsic coupling.

Early life stress moderated the influence of reward anticipation on acute psychosocial stress responses

Recent studies suggest that reward anticipation decreases individuals' acute stress responses. However, individuals who have experienced early life stress (ELS) may have a blunted capacity for reward anticipation, which reduces its buffering effect on psychosocial stress responses. To investigate this phenomenon, 66 young adults completed the Trier Social Stress Test following a reward anticipation task, and their ELS levels were measured using the Childhood Trauma Questionnaire (CTQ). Meanwhile, the current study collected biological and psychological measures of stress by analysing cortisol levels, heart rates, heart rate variability (HRV) as well as subjective stress levels, in response to the Trier Social Stress test. Results showed that reward anticipation successfully decreased acute stress responses in general, and it also improved participants' HRV. However, this effect was more evident in individuals with low ELS than those with high ELS. These findings help us deepen understanding of the role of reward anticipation in fostering resilience under stress and the potentially important implications for individuals who have been exposed to ELS are also discussed.