Date of Award

6-2026

Degree Type

Thesis

Degree Name

Master of Science

Department

Psychological Science

Program

Psychological Science (MS)

First Advisor/Chairperson

Joshua Carlson

Abstract

Reward processing is essential in everyday life and is related to symptoms of mental health diagnoses. The reward positivity (RewP) is an electroencephalogram (EEG)-based measure sensitive to rewarding vs non-rewarding outcomes, that is measured by electrodes on the scalp which detect brain activity following reward feedback. One area implicated as a neural generator of the RewP is the dorsal anterior cingulate cortex (dACC) due to its associations with other regions associated with the RewP (Heilbronner & Hayden, 2016). Despite the potential influence of the dACC, this region has yet to be causally linked (Oerlemans et al., 2024). Transcranial alternating current stimulation (tACS) was used, which utilizes frequencies to entrain the brain’s oscillations, to establish causality. Participants were recruited from a Midwest public university and the surrounding community. They were asked baseline questionnaires to assess affect, trait levels of depression, anxiety, and stress, adverse effect symptoms, and reward responsiveness. Then participants were randomly assigned to either the theta-band tACS or the sham group prior to the paradigm. Afterwards, participants completed post-intervention questionnaires measuring positive and negative affect, post-neuromodulation effects, motivation. The results found that the win trials were significantly greater in both of the groups, along with a greater difference in the experimental group and a significant interaction between type of group and reward. However, there was no significant differences regarding change in affect. This study was to examine the role of the dACC on the RewP along with the efficacy of tACS on reward processing for potential, future clinical use.

Access Type

Open Access

Justification for Restricting Access

The 5-year embargo request is due to a desire to publish the results of this thesis in a reputable, academic journal. The goal is to do accomplish this desire within the next 5 years (maybe sooner) and will help me develop the skills to publish more works in my scientific career. This would also be my first publication, which will help with building my skillset and further preparation for future education and research.

Additional Files
Eric Rodell.pdf (279 kB)
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Available for download on Sunday, July 06, 2031

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