Developmental history and stress responsiveness are related to response inhibition, but not judgement bias, in a cohort of European starlings (Sturnus vulgaris)

Annie Gott,Clare Andrews,Tom Bedford,Melissa Bateson,Daniel Nettle

doi:10.1007/s10071-018-1226-7

Abstract

Judgement bias tasks are designed to provide markers of affective states. A recent study of European starlings (Sturnus vulgaris) demonstrated modest familial effects on judgement bias performance, and found that adverse early experience and developmental telomere attrition (an integrative marker of biological age) both affected judgement bias. Other research has shown that corticosterone levels affect judgement bias. Here, we investigated judgement bias using a modified Go/No Go task in a new cohort of starlings (n = 31) hand-reared under different early-life conditions. We also measured baseline corticosterone and the corticosterone response to acute stress in the same individuals. We found evidence for familial effects on judgement bias, of a similar magnitude to the previous study. We found no evidence that developmental treatments or developmental telomere attrition were related to judgement bias per se. We did, however, find that birds that experienced the most benign developmental conditions, and birds with the greatest developmental telomere attrition, were significantly faster to probe the learned unrewarded stimulus. We also found that the birds whose corticosterone levels were faster to return towards baseline after an acute stressor were slower to probe the learned unrewarded stimulus. Our results illustrate the potential complexities of relationships between early-life experience, stress and affectively mediated decision making. For judgement bias tasks, they demonstrate the importance of clearly distinguishing factors that affect patterns of responding to the learned stimuli (i.e. response inhibition in the case of the Go/No Go design) from factors that influence judgements under ambiguity.

Highlights

In humans, exposure to early-life adversity has been repeatedly linked to the development of affective disorders such as depression and anxiety (Parker et al 1995; Sadowski et al 1999; Kendler et al 2002; Heim et al 2008)
We found no significant effects of developmental treatments or ΔTL on days to pass discrimination learning; nor any significant correlations with CORT variables
We found an effect of early-life adversity on latency to probe the negative learned stimulus, but in our case, the birds with the most benign early conditions, and the fastest weight gain during development, were the ones that were fastest to probe

Summary

Introduction

Exposure to early-life adversity has been repeatedly linked to the development of affective disorders such as depression and anxiety (Parker et al 1995; Sadowski et al 1999; Kendler et al 2002; Heim et al 2008). Judgement bias paradigms are motivated by the fact that depressed and anxious humans tend to interpret ambiguous information in the more negative of its possible ways (Ouimet et al 2009; Everaert et al 2017). These biases are not restricted to clinically diagnosed disorders, but are found in individuals with sub-clinical symptoms and those in remission (Everaert et al 2017), suggesting that judgement biases index chronic negative affect. There is some evidence that adverse childhood experiences are linked to the negative cognitive biases found in depression (Günther et al 2015)

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