AbstractThis thesis aimed to evaluate whether EEG is a sensitive measure of reward dysfunction in alcohol dependency using a monetary incentive delay task. fMRI monetary incentive delay task studies have shown significant differences exist between alcohol dependent and healthy control participants, with alcohol dependent participants showing blunted ventral striatum activation during the anticipation of monetary rewards (Wrase et al., 2007; Beck et al., 2009) and an elevated response in a distributed reward network during reward outcome (Bjork et al., 2008; Luijten et al., 2017). To date, an EEG monetary incentive delay task has not been used to assess reward disturbances in alcohol dependency or other addictive disorders. This thesis provides new insights into this topic, describing three EEG monetary incentive delay experiments in which data were analysed using both event-related potential and multivariate single-trial machine learning methods.
Experiment 1 found disrupted valence (monetary gain versus loss cues) sensitivity during reward anticipation within a group of young adult at-risk drinkers. The machine learning analyses demonstrated that low-risk drinkers have significant valence discrimination within the cue-P3 time window, whereas at-risk drinkers were insensitive to valence. Experiment 2 uncovered reduced cue-P3 sensitivity to gain and loss anticipation in alcohol dependent compared to healthy control participants. The event-related potential analyses showed enhanced cue-P3 amplitudes for both monetary gain and monetary loss compared to neutral cues within healthy controls, but this effect was not observed in alcohol dependents. The machine learning analyses demonstrated healthy controls had enhanced loss anticipation discrimination (monetary loss versus neutral cues) across the cue-P3 time window. Experiment 3 found no evidence of disrupted reward processing in alcohol dependent compared to healthy control participants during the outcome phase of the task. Both groups showed comparable results for both forms of analyses, with modulation by reward predication error salience and valence within the FRN and the feedback-P3 time windows, respectively.
This thesis found blunted neural processing within the cue-P3 time window during reward anticipation in a group of at-risk drinkers and alcohol dependent participants, compared to healthy controls. The experiments in this thesis uncovered potential EEG components which may be utilised during future psychopharmacological research for the evaluation of treatments for alcohol dependency.
|Date of Award||19 May 2023|
|Supervisor||Anna Murphy (Main Supervisor) & Chris Retzler (Co-Supervisor)|