UBC Theses and Dissertations
Individual differences in development and representation of novel affective associations Ehlers, Mana R.
Emotionally arousing events are typically better remembered than mundane ones, in part because emotionally relevant aspects of our environment are prioritized in attention. Such biased attentional tuning is itself the result of associative processes through which we learn affective and motivational relevance of cues. While such affective biases in cognition can be highly adaptive, extreme biases to specific categories of aversive or rewarding stimuli can be symptomatic of psychopathology. That raises the question which factors contribute to individual differences in development of affective biases via emotional learning processes and how emotional associations come to be represented in the brain. More specifically, the present thesis aimed to investigate the role of individual differences in the norepinephrine and stress system in emotional learning processes. In Study I, I demonstrated that a common genetic variation putatively influencing norepinephrine availability is associated with subjective perception of ambiguous stimuli as more rewarding. Moreover, change in affective bias was mediated by acute stress. Thus, in the first study I established that individual differences in the locus coeruleus-norepinephrine (LC-NE) and stress system play a role in affective perception and the flexibility of the underlying subjective biases. In Study II and III, I found that acute stress affects both classical and operant conditioning and that the direction of those effects depends on the timing of the stressor relative to the learning experience. Study IV aimed to investigate the neural representation of the development of novel affective associations using functional magnetic resonance imaging (fMRI). By means of representational similarity analysis (RSA) - a multivariate approach to analyzing neuroimaging data - the study revealed that conditioned stimuli reactivate the representational pattern elicited by the unconditioned stimuli. I further observed that it is specifically the hedonic response to the unconditioned stimulus that is being reproduced by the conditioned stimulus. Together these studies demonstrate a role for the norepinephrine and stress system in reward-based learning as well as providing new information of neural mechanisms underlying emotional learning. This research provides insight into individual differences in emotional learning processes that can underlie formation of affective biases.
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