Researcher ORCID Identifier


Graduation Year


Document Type

Campus Only Senior Thesis

Degree Name

Bachelor of Arts



Reader 1

Melissa Coleman

Reader 2

Thomas Borowski

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Cocaine addiction poses a major public health issue as it affects approximately 1.3 million Americans per year. Cocaine, like all addictive substances, causes dopamine to be released into the nucleus accumbens. This can be caused by dopaminergic neurons in the ventral tegmental area (VTA), and these VTA neurons can be activated by glutamate release from the dorsal raphe (DR). There is a subpopulation of DR neurons that co-releases serotonin and glutamate, and these are identified by the transporters they express: the serotonin reuptake transporter (SERT) and the vesicular glutamate transporter type 3 (VGluT3). The aim of this study was to determine the role of DR dual SERT-VGluT3 expressing neurons that project to the VTA in cocaine-seeking behavior. Because of the established involvement of glutamate and serotonin in reward, it was predicted that selectively activating these neurons would be rewarding. This experiment used a mouse model with place preference assays and optogenetic stimulation targeting DR dual SERT-VGluT3 synapses in the VTA. Place preference acquisition and reinstatement after extinction was tested using both photostimulation and cocaine conditioning. If this subpopulation of DR neurons does have a role in reward and in cocaine-seeking behavior, then there will be a significant place preference conditioned by the photostimulation alone and a reinstatement of cocaine-seeking behavior following photostimulation after the behavior is extinguished. This will clarify the role of DR dual SERT-VGluT3 neurons in the circuitry of reward.

This thesis is restricted to the Claremont Colleges current faculty, students, and staff.