Investigating the neural mechanisms of aversive learning: predictions, prediction errors and the effects of contextual novelty

The ability to detect and respond to motivationally relevant information is crucial for survival. While the dopaminergic mesolimbic system, including substantia nigra / ventral tegmental area and nucleus accumbens, has long been associated with reward learning, recent evidence shows that it also codes aversive events. Although this points towards a much more general role in salience processing, it remains unclear whether the mesolimbic system follows a unified coding strategy in aversive and appetitive learning. On the basis of my previous studies, I plan to address this apparent gap in our understanding of basic learning mechanisms by using intracranial recordings in humans (iEEG) as well as combined EEG/fMRI together with psychopharmacology and behavioral tests. This multimodal approach allows a characterization of the underlying neural processes with high temporal and spatial resolution and it offers direct conclusions regarding the role of dopamine. As such, this work will give new and important insights into the functional properties of the human mesolimbic system in aversive learning. From a more clinical perspective, it might allow us to establish new markers of how the healthy brain predicts and adapts to painful stimulation, which is altered in patients suffering from chronic pain.

In this project, we aimed to further investigate and specify the role of the mesolimbic system in processing aversive events. We used a variety of behavioral paradigms, MEG, iEEG and fMRI to show that (a) anticipation of aversive events recruits the mesolimbic system and differentially modulates subsequent recognition memory, (b) neural habituation to painful stimuli is modulated by dopamine, and (c) that alpha-beta oscillations in the substantia nigra signal the anticipation of both appetitive and aversive events. As such, our findings provide novel insights into the psychological and physiological mechanisms of aversive processing, and, from a more general perspective, they underline that the dopaminergic mesolimbic system plays a critical role in processing both appetitive and aversive events.