Item type:Thesis, Open Access

Electrocortical signatures of prediction error processing during threat avoidance and monetary reward learning

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Approaching reward and avoiding punishment or threat are fundamental ways in which organisms adapt to changing environments. Achieving these motivational goals demands cognitive and affective control, broadly defined as the ability of neurocognitive systems to flexibly organize cognition and behaviour in non-affective and affective situations. In affective and non-affective reinforcement learning, expectations and their violations, i.e., prediction errors (PEs) are central for successful reward and threat avoidance learning. PEs can either be defined as unsigned, reflecting any surprising outcome, or signed, indicating better-thanexpected (positive, PE+) or worse-than-expected (negative, PE−) outcomes. In the electroencephalogram (EEG), PE processing and other control mechanisms often have often been linked to frontal midline theta (FMθ, 4–8 Hz). According to the adaptive control hypothesis (TACH), FMθ plays a key role in indexing control processes during reward maximization and the regulation of negative affective states. Thus, feedback signalling monetary non-reward or threat, and high levels of reward and threat PEs are hypothesized to increase FMθ. Moreover, TACH also makes assumptions about FMθ functioning in individuals high vs. low in negative affective personality traits, especially trait neuroticism/anxiety. Specifically, FMθ is expected to be amplified in highly neurotic/anxious individuals. Other relevant EEG markers in feedback and PE processing include slow wave delta-band (1–4 Hz) oscillations and the phase-locked Reward Positivity (RewP), both linked to PE+ processing, and the salience-sensitive P300. However, most EEG research on reinforcement learning focused involved monetary reward rather than primary threat reinforcer. Thus, the processes involved in threat avoidance learning and its links to individual differences in trait neuroticism/anxiety are poorly understood. The present thesis addresses this gap by examining electrocortical responses to expected and unexpected feedback in reward gain vs. threat avoidance learning, and their associations with individual differences in trait neuroticism/anxiety. In both studies of the present thesis, we measured EEG activity in two reinforcement learning tasks with different reinforcers following positive vs. negative feedback. In the reward learning task, feedback signalled monetary reward vs. monetary non-reward, whereas in the threat avoidance learning task, feedback signalled the successful avoidance of a loud noise burst vs. its presentation. To my knowledge, these are the first studies in which the intensity of the monetary reward and primary threat reinforcer were titrated to ensure meaningful taskcomparisons. PEs were comprehensively measured via computational modelling (estimated PEs, ePEs) as well as self-reported trial-by-trial expectations (self-reported PEs, sPEs). In Study I, we replicated the often-reported feedback valence effect in the reward task, with amplified FMθ responses to monetary non-reward vs. monetary reward. There was also a feedback valence effect in the threat avoidance learning task, indicating increased FMθ responses to feedback signalling threat vs. successful avoidance/safety, although this effect was substantially smaller than in the reward task. Moreover, we found no evidence for a link between FMθ and reward and threat prediction errors (ePE & sPE), and explorative analyses revealed no significant influence of PEs on the feedback valence effects. In Study II, we strongly focused on reward and threat PE+ since comparisons of positive feedback trials between reward and threat avoidance learning were less confounded by potential defensive preparation responses before threat onset. We found that FMθ positively scaled with the computationally derived ePE+ in both, the reward learning and threat avoidance learning task. There were no significant correlations between trait neuroticism/anxiety and cognitive/affective control except of a marginal and selective positive moderation of the link between FMθ and reward ePE+. Moreover, reward ePE+ were stronger positively correlated to the RewP and exclusively to delta-band activity, while threat ePE+ were stronger linked to the P300. The importance of the P300 in reinforcement learning was further supported by its role in predicting subsequent behavioural adaptation and by exploratory analyses of ePE−. The present thesis provides first evidence on affective and cognitive control in a direct comparison of reward and threat avoidance learning. Our studies suggest that while FMθ can be considered an index for cognitive and affective control, it may not represent a simple on-off signal but instead shows activity patterns that may depend on the learning context and specific task demands. The mixed findings on the relationship between trait neuroticism/anxiety and FMθ, including null results for the conceptually closer threat avoidance learning, were discussed in relation to present challenges in personality neuroscience. The dissociable sensitivity of the RewP in reward-related, and the P300 in threat-related reinforcement learning may point to different representations of the neural reward and threat system. Overall, the results of the present thesis particularly contribute to a better understanding of the electrocortical mechanisms underlying threat avoidance learning and provide a helpful starting point for future research on threat-related reinforcement learning.

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Stolz, Christopher: Electrocortical signatures of prediction error processing during threat avoidance and monetary reward learning. : 2025-12-10.

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Except where otherwised noted, this item's license is described as CC BY-NC-SA 4.0