Honors Theses

Date of Award

Winter 12-12-2025

Document Type

Undergraduate Thesis

Department

Chemistry and Biochemistry

First Advisor

Alberto Del Arco

Second Advisor

Ryan Fortenberry

Third Advisor

Kenneth Sufka

Relational Format

Dissertation/Thesis

Abstract

A fundamental concept of human nature is the desire for reward and avoidance of punishment. Animals undergo a decision-making process, which is a cognitive process of selecting an option among a group based on personal preferences. Value-based decision-making is how individuals evaluate and compare potential outcomes, taking risk, delay, effort, and subjective preferences into consideration. Individuals with drug use disorders often show impairments in processing reward-related information and in regulating their behavior when the pursuit of immediate rewards with long-term goals or negative consequences. Choice impulsivity is a value-based decision-making bias and one of the most reliable behavioral features that anticipates the transition to substance abuse. Clinical trials suggest that a single injection of the psychedelic drug, psilocybin, can produce acute and long-term therapeutic benefits for psychiatric disorders. Based on these studies, we investigated if one single dose of psilocybin would reduce impulsivity in rats concerning reward decision-making, therefore making the drug a potential treatment for individuals struggling with substance abuse. Male Long Evans rats were trained on a delay discounting task to assess choice impulsivity. They chose between a small immediate reward and a larger reward delivered after increasing delays (1, 10, or 20 s). After consistent performance with the task, the rats received a single injection of psilocybin (1 mg/kg) or vehicle, followed by 60 minutes of head-twitch behavior monitoring. The rats completed the task again at 24 and 48 hours after injections. Results of the behavioral task showed psilocybin decreased large reward choices for rats specifically 48 hours after injections. These results were not dependent on delay and are therefore consistent with psilocybin decreasing reward-seeking behavior during the task.

Creative Commons License

Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.

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