Undergraduate Honors Theses

Thesis Defended

Spring 2018

Document Type


Type of Thesis

Departmental Honors


Psychology & Neuroscience

First Advisor

Marie Banich


The inhibitory neurotransmitter γ-Aminobutyric acid (GABA) and the excitatory neurotransmitter glutamate are the most abundant neurotransmitters in the brain. Together these neurotransmitter systems have been implicated in brain regions related to executive function, specifically, in the ventral lateral prefrontal cortex (VLPFC) and the dorsal lateral prefrontal cortex (DLPFC). One measure of executive function that these systems influence, is the process of obtaining a winning option amongst competing alternatives, known as selection. Selection can be split into two categories; underdetermined selection and prepotent selection. Underdetermined selection refers to selection amongst many task related options while prepotent selection refers to the ability to select relevant information in the face of a dominant option that is task irrelevant. Moreover, previous studies have shown a relationship between selection and traits related to psychopathology, such as anxiety and depression. The current study seeks to examine the pathways linking GABA to regional brain activation in the prefrontal cortex to performance on selection based cognitive tasks and to traits related to psychopathology. Using MR spectroscopy, GABA levels were measured in the VLPFC and fMRI was used to measure brain activation during a selection based, verb generation task. Levels of anxiety and depression were measured through the Penn State Worry Questionnaire (PSWQ) and the Mood and Anxiety Symptoms Questionnaire (MASQ). The results show a significant negative correlation between VLPFC GABA concentration and performance on underdetermined selection tasks suggesting that levels of neurotransmitter in the prefrontal cortex can influence the degree to which an individual exerts executive control.