Doctor of Philosophy (PhD)
Motivation deficits (i.e., avolition or amotivation) are a cardinal feature of schizophrenia spectrum disorders (SSDs) and are linked to worse functional outcomes. Accumulating evidence implicates underactive dopamine responses in reward areas of the brain (e.g., striatum) in the etiology of amotivation. Phasic dopamine firing in the striatum purportedly has a role in increasing the perceived value of a potential reward that, in effect, helps “push” the organism toward initiating and persisting in the action to pursue rewards. Previous research has suggested that eye blink rate (EBR) may be a reliable and valid index of striatal dopamine. Amotivation (clinician-rated and self-reported) and phasic changes in EBR on an effort-based reward task were assessed in 28 stable outpatients with an SSD. Overall, the paradigm detected robust changes in blink rate across task phases; however, the pattern of changes was not in the direction hypothesized. Moderation analyses were used to examine the influence of various factors (pre-task state affect, expectations, and behavioral performance) on the relationships between baseline and reward task phases (i.e., reward anticipation and reward receipt). Results revealed that greater behavioral effort was associated with lower EBR during Reward Receipt. Higher anticipated monetary reward was associated with lower EBR during Reward Anticipation and Reward Receipt. Positive affect and self-reported amotivation moderated the relationship between Reward Anticipation EBR and Reward Receipt EBR, such that lower positive affect and higher amotivation weakened the relationship between those conditions. Changes in blink rate appeared better accounted for by literature supporting the inverse relationship between blink rate and task engagement. Implications for understanding the relationship between EBR and amotivation are discussed.
McGovern, Jessica Elaina, "The (B)link Between Amotivation and Dopamine in Psychosis: What Phasic Eye Blink Rate Reveals" (2018). LSU Doctoral Dissertations. 4697.
Available for download on Friday, August 30, 2019