Sinem Balta Beylergil, GRK 1589 / TU Berlin

Modeling Cognitive Flexibility in Alcohol Dependence

Alcohol-dependent individuals often lack the ability to adjust decisions flexibly in response to changes in reward contingencies. The main objective of this thesis is to understand the computational and neural processes underlying the impaired cognitive flexibility in alcohol dependence by combining reinforcement learning (RL) models with functional magnetic resonance imaging (fMRI). The defense talk will consist of three parts. The first part will cover the modeling of the behavioral data acquired from 34 abstinent alcohol-dependent patients (ADP) and 26 healthy controls (HC) during a probabilistic reward-guided decision-making task with dynamically changing reinforcement contingencies. Using a modified Rescorla-Wagner type model, which models the underlying computations carried out by subjects to solve the current decision-making problem, I will demonstrate that ADP had decreased sensitivity for punishments compared to HC. During the second part of the talk, I will present a reduced correlation between the bilateral dorsolateral prefrontal cortex (DLPFC) activity in ADP and the prediction error (PE) signal, which is thought to mediate flexible decision making by monitoring the difference between expected and received outcomes. The focus will be on the left DLPFC activity, which showed reduced tracking of negative PEs, which facilitate the extinction of learned responses. In the third and final part, I will present the findings of a psychophysiological interactions connectivity analysis, in which the coupling between the bilateral DLPFC and other brain regions was moderated by the PE signal. I will demonstrate disrupted information flow in ADP between the bilateral DLPFC and the medial prefrontal cortex including the rostral anterior cingulate cortex; and enhanced connectivity in ADP between the left DLPFC and the right hippocampus including the right parahippocampal gyrus.

 

Additional Information

PhD defence in the GRK 1589 "Sensory Computation in Neural Systems"

Organized by

Klaus Obermayer / Robert Martin