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Date of Award


Document Type

Restricted Thesis: Campus only access

Degree Name

Bachelor of Science



First Advisor

Dr. Kelly Lambert


Major Depressive Disorder (MDD) has a huge impact on our society, being a leading cause of disability worldwide. The current study focuses on a preventative approach to MDD, in the form of effort-based reward (EBR) contingency training. Twenty animals were trained to associate physical effort with a food reward using this model, while twenty animals served as controls and were simply given the reward. Animals were then assessed on a hippocampal-dependent pattern separation task and an uncertainty task, as well as on endocrine and neurobiological markers of emotional resilience. Results showed that contingent trained animals performed better that non-contingent animals on the hippocampal-dependent pattern separation assessment when the task was hardest. EBR animals also exhibited a lower activation of the lateral habenula, a brain region that is overactive in MDD. Preliminary data also show a higher ratio of GRIN2B/2A, genes that code for NMDA receptor subtypes, in the dentate gyrus of the contingent trained group, a ratio that has been linked to flexible problem solving. Taken together, data from this study show that contingency training is associated with a shift from emotional vulnerability to emotional resilience, making it a potentially effective way to prevent disorders like MDD.