Date of Award

Spring 2020

Project Type

Thesis

Program or Major

Psychology

Degree Name

Master of Arts

First Advisor

Jill McGaughy

Second Advisor

Robert Ross

Third Advisor

Caitlin Mills

Abstract

The anterior cingulate cortex (ACC) has been shown to activate when situations are in conflict, when determining the relevance of stimuli, and error processing. Dopaminergic projections to the ACC are hypothesized to facilitate the integration of incoming stimuli with error signals to select and maintain the optimal task set, reducing the liability to distraction. In previous work, rodents with excitotoxic lesions to the ACC showed increased susceptibility to distraction when a complex stimulus contained a stimulus dimension with a prior reward history. In an expansion of this work, following dopaminergic lesions to the ACC rodents were tested in an attentional set shifting task and a sustained attention task. In experiment 1, all subjects showed increased susceptibility to distraction, and either an inability to update reinforcement contingencies or an inability to overcome the increased susceptibility to distraction. Experiment 2 explicitly tested the ability of subjects to filter novel distractors with no prior reinforcement history, as well as the ability to update reinforcement contingencies without distractors present. Dopamine lesions did not increase susceptibility to distraction from novel distractors and did not globally impair the ability to update reinforcement contingencies. All males showed an ability to adjust to changes in reinforcement regardless of the delay, females, however, showed a specific inability to adjust only when reinforcement was delayed 2s. The difference in males and female’s ability to adjust to changes in reinforcement in the sustained attention task requires further research. Together the experiments suggest that dopamine dysfunction in the ACC is sufficient to increase susceptibility to distraction when complex stimuli dimensions have a prior reinforcement history.

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