Differentiating associations between tasks and outcomes in the human brain
Date
2022
Authors
Nelson, Lauren, author
Seger, Carol, advisor
Thomas, Michael, committee member
Anderson, Chuck, committee member
Tompkins, Sara Anne, committee member
Journal Title
Journal ISSN
Volume Title
Abstract
In order to successfully achieve their goals in a noisy and changing environment, organisms must continually learn both Pavlovian (stimulus-outcome or S-O) and instrumental (action-outcome or A-O) associations. A wide range of brain regions are implicated in reinforcement learning and decision-making, including the basal ganglia, medial prefrontal cortex, the dorsolateral prefrontal cortex (dlPFC), and the anterior cingulate cortex (ACC). One possible explanation of disparate findings is that activation depends on the nature of the action or response under consideration. To investigate representations of task-reward associations, subjects switched between an emotional judgement task and a spatial judgement task, combined with either a high or low level of reward. A general linear model (GLM) compared activation for different combinations of task and reward. A cluster in the mid-prefrontal cortex was more active for right versus left response, whereas a cluster in the midbrain near the brainstem was more active for left responses. Performance of the spatial task was associated with activation in the ventral occipital cortex and ventral prefrontal cortex. Clusters in the posterior parietal cortex and lateral prefrontal cortex were more active during the emotion task. Receiving a large reward was accompanied by activation in primary somatosensory cortex and auditory cortex, while receiving a low reward appeared to recruit the anterior cingulate cortex. Comparing trials which yielded a reward versus trials with no reward revealed activation in the dorsal prefrontal cortex. A 2-way ANOVA examining independent contributions of response and reward found an effect of response in cuneus and pre-cuneus, an effect of reward in anterior insula and sensorimotor cortex, and an interaction in the post-central gyrus. A 2-way ANOVA of task and reward found a main effect of task in several clusters in the medial occipital cortex, a main effect of reward in somatosensory cortex and anterior insula, and an interaction in the ventral occipital and anterior prefrontal cortex.